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2020-06-11signal: Extend exec_id to 64bitsEric W. Biederman
commit d1e7fd6462ca9fc76650fbe6ca800e35b24267da upstream. Replace the 32bit exec_id with a 64bit exec_id to make it impossible to wrap the exec_id counter. With care an attacker can cause exec_id wrap and send arbitrary signals to a newly exec'd parent. This bypasses the signal sending checks if the parent changes their credentials during exec. The severity of this problem can been seen that in my limited testing of a 32bit exec_id it can take as little as 19s to exec 65536 times. Which means that it can take as little as 14 days to wrap a 32bit exec_id. Adam Zabrocki has succeeded wrapping the self_exe_id in 7 days. Even my slower timing is in the uptime of a typical server. Which means self_exec_id is simply a speed bump today, and if exec gets noticably faster self_exec_id won't even be a speed bump. Extending self_exec_id to 64bits introduces a problem on 32bit architectures where reading self_exec_id is no longer atomic and can take two read instructions. Which means that is is possible to hit a window where the read value of exec_id does not match the written value. So with very lucky timing after this change this still remains expoiltable. I have updated the update of exec_id on exec to use WRITE_ONCE and the read of exec_id in do_notify_parent to use READ_ONCE to make it clear that there is no locking between these two locations. Link: https://lore.kernel.org/kernel-hardening/20200324215049.GA3710@pi3.com.pl Fixes: 2.3.23pre2 Cc: stable@vger.kernel.org Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com> [bwh: Backported to 3.16: - Use ACCESS_ONCE() - Adjust context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
2020-05-22clocksource: Prevent double add_timer_on() for watchdog_timerKonstantin Khlebnikov
commit febac332a819f0e764aa4da62757ba21d18c182b upstream. Kernel crashes inside QEMU/KVM are observed: kernel BUG at kernel/time/timer.c:1154! BUG_ON(timer_pending(timer) || !timer->function) in add_timer_on(). At the same time another cpu got: general protection fault: 0000 [#1] SMP PTI of poinson pointer 0xdead000000000200 in: __hlist_del at include/linux/list.h:681 (inlined by) detach_timer at kernel/time/timer.c:818 (inlined by) expire_timers at kernel/time/timer.c:1355 (inlined by) __run_timers at kernel/time/timer.c:1686 (inlined by) run_timer_softirq at kernel/time/timer.c:1699 Unfortunately kernel logs are badly scrambled, stacktraces are lost. Printing the timer->function before the BUG_ON() pointed to clocksource_watchdog(). The execution of clocksource_watchdog() can race with a sequence of clocksource_stop_watchdog() .. clocksource_start_watchdog(): expire_timers() detach_timer(timer, true); timer->entry.pprev = NULL; raw_spin_unlock_irq(&base->lock); call_timer_fn clocksource_watchdog() clocksource_watchdog_kthread() or clocksource_unbind() spin_lock_irqsave(&watchdog_lock, flags); clocksource_stop_watchdog(); del_timer(&watchdog_timer); watchdog_running = 0; spin_unlock_irqrestore(&watchdog_lock, flags); spin_lock_irqsave(&watchdog_lock, flags); clocksource_start_watchdog(); add_timer_on(&watchdog_timer, ...); watchdog_running = 1; spin_unlock_irqrestore(&watchdog_lock, flags); spin_lock(&watchdog_lock); add_timer_on(&watchdog_timer, ...); BUG_ON(timer_pending(timer) || !timer->function); timer_pending() -> true BUG() I.e. inside clocksource_watchdog() watchdog_timer could be already armed. Check timer_pending() before calling add_timer_on(). This is sufficient as all operations are synchronized by watchdog_lock. Fixes: 75c5158f70c0 ("timekeeping: Update clocksource with stop_machine") Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lore.kernel.org/r/158048693917.4378.13823603769948933793.stgit@buzz Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
2020-05-22tracing: Fix tracing_stat return values in error handling pathsLuis Henriques
commit afccc00f75bbbee4e4ae833a96c2d29a7259c693 upstream. tracing_stat_init() was always returning '0', even on the error paths. It now returns -ENODEV if tracing_init_dentry() fails or -ENOMEM if it fails to created the 'trace_stat' debugfs directory. Link: http://lkml.kernel.org/r/1410299381-20108-1-git-send-email-luis.henriques@canonical.com Fixes: ed6f1c996bfe4 ("tracing: Check return value of tracing_init_dentry()") Signed-off-by: Luis Henriques <luis.henriques@canonical.com> [ Pulled from the archeological digging of my INBOX ] Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
2020-05-22tracing: Fix very unlikely race of registering two stat tracersSteven Rostedt (VMware)
commit dfb6cd1e654315168e36d947471bd2a0ccd834ae upstream. Looking through old emails in my INBOX, I came across a patch from Luis Henriques that attempted to fix a race of two stat tracers registering the same stat trace (extremely unlikely, as this is done in the kernel, and probably doesn't even exist). The submitted patch wasn't quite right as it needed to deal with clean up a bit better (if two stat tracers were the same, it would have the same files). But to make the code cleaner, all we needed to do is to keep the all_stat_sessions_mutex held for most of the registering function. Link: http://lkml.kernel.org/r/1410299375-20068-1-git-send-email-luis.henriques@canonical.com Fixes: 002bb86d8d42f ("tracing/ftrace: separate events tracing and stats tracing engine") Reported-by: Luis Henriques <luis.henriques@canonical.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
2020-05-22padata: always acquire cpu_hotplug_lock before pinst->lockDaniel Jordan
commit 38228e8848cd7dd86ccb90406af32de0cad24be3 upstream. lockdep complains when padata's paths to update cpumasks via CPU hotplug and sysfs are both taken: # echo 0 > /sys/devices/system/cpu/cpu1/online # echo ff > /sys/kernel/pcrypt/pencrypt/parallel_cpumask ====================================================== WARNING: possible circular locking dependency detected 5.4.0-rc8-padata-cpuhp-v3+ #1 Not tainted ------------------------------------------------------ bash/205 is trying to acquire lock: ffffffff8286bcd0 (cpu_hotplug_lock.rw_sem){++++}, at: padata_set_cpumask+0x2b/0x120 but task is already holding lock: ffff8880001abfa0 (&pinst->lock){+.+.}, at: padata_set_cpumask+0x26/0x120 which lock already depends on the new lock. padata doesn't take cpu_hotplug_lock and pinst->lock in a consistent order. Which should be first? CPU hotplug calls into padata with cpu_hotplug_lock already held, so it should have priority. Fixes: 6751fb3c0e0c ("padata: Use get_online_cpus/put_online_cpus") Signed-off-by: Daniel Jordan <daniel.m.jordan@oracle.com> Cc: Eric Biggers <ebiggers@kernel.org> Cc: Herbert Xu <herbert@gondor.apana.org.au> Cc: Steffen Klassert <steffen.klassert@secunet.com> Cc: linux-crypto@vger.kernel.org Cc: linux-kernel@vger.kernel.org Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
2020-05-22padata: purge get_cpu and reorder_via_wq from padata_do_serialDaniel Jordan
commit 065cf577135a4977931c7a1e1edf442bfd9773dd upstream. With the removal of the padata timer, padata_do_serial no longer needs special CPU handling, so remove it. Signed-off-by: Daniel Jordan <daniel.m.jordan@oracle.com> Cc: Herbert Xu <herbert@gondor.apana.org.au> Cc: Steffen Klassert <steffen.klassert@secunet.com> Cc: linux-crypto@vger.kernel.org Cc: linux-kernel@vger.kernel.org Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
2020-05-22padata: Remove broken queue flushingHerbert Xu
commit 07928d9bfc81640bab36f5190e8725894d93b659 upstream. The function padata_flush_queues is fundamentally broken because it cannot force padata users to complete the request that is underway. IOW padata has to passively wait for the completion of any outstanding work. As it stands flushing is used in two places. Its use in padata_stop is simply unnecessary because nothing depends on the queues to be flushed afterwards. The other use in padata_replace is more substantial as we depend on it to free the old pd structure. This patch instead uses the pd->refcnt to dynamically free the pd structure once all requests are complete. Fixes: 2b73b07ab8a4 ("padata: Flush the padata queues actively") Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Reviewed-by: Daniel Jordan <daniel.m.jordan@oracle.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
2020-05-22padata: initialize pd->cpu with effective cpumaskDaniel Jordan
commit ec9c7d19336ee98ecba8de80128aa405c45feebb upstream. Exercising CPU hotplug on a 5.2 kernel with recent padata fixes from cryptodev-2.6.git in an 8-CPU kvm guest... # modprobe tcrypt alg="pcrypt(rfc4106(gcm(aes)))" type=3 # echo 0 > /sys/devices/system/cpu/cpu1/online # echo c > /sys/kernel/pcrypt/pencrypt/parallel_cpumask # modprobe tcrypt mode=215 ...caused the following crash: BUG: kernel NULL pointer dereference, address: 0000000000000000 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 0 P4D 0 Oops: 0000 [#1] SMP PTI CPU: 2 PID: 134 Comm: kworker/2:2 Not tainted 5.2.0-padata-base+ #7 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-<snip> Workqueue: pencrypt padata_parallel_worker RIP: 0010:padata_reorder+0xcb/0x180 ... Call Trace: padata_do_serial+0x57/0x60 pcrypt_aead_enc+0x3a/0x50 [pcrypt] padata_parallel_worker+0x9b/0xe0 process_one_work+0x1b5/0x3f0 worker_thread+0x4a/0x3c0 ... In padata_alloc_pd, pd->cpu is set using the user-supplied cpumask instead of the effective cpumask, and in this case cpumask_first picked an offline CPU. The offline CPU's reorder->list.next is NULL in padata_reorder because the list wasn't initialized in padata_init_pqueues, which only operates on CPUs in the effective mask. Fix by using the effective mask in padata_alloc_pd. Fixes: 6fc4dbcf0276 ("padata: Replace delayed timer with immediate workqueue in padata_reorder") Signed-off-by: Daniel Jordan <daniel.m.jordan@oracle.com> Cc: Herbert Xu <herbert@gondor.apana.org.au> Cc: Steffen Klassert <steffen.klassert@secunet.com> Cc: linux-crypto@vger.kernel.org Cc: linux-kernel@vger.kernel.org Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
2020-05-22padata: Replace delayed timer with immediate workqueue in padata_reorderHerbert Xu
commit 6fc4dbcf0276279d488c5fbbfabe94734134f4fa upstream. The function padata_reorder will use a timer when it cannot progress while completed jobs are outstanding (pd->reorder_objects > 0). This is suboptimal as if we do end up using the timer then it would have introduced a gratuitous delay of one second. In fact we can easily distinguish between whether completed jobs are outstanding and whether we can make progress. All we have to do is look at the next pqueue list. This patch does that by replacing pd->processed with pd->cpu so that the next pqueue is more accessible. A work queue is used instead of the original try_again to avoid hogging the CPU. Note that we don't bother removing the work queue in padata_flush_queues because the whole premise is broken. You cannot flush async crypto requests so it makes no sense to even try. A subsequent patch will fix it by replacing it with a ref counting scheme. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> [bwh: Backported to 3.16: Deleted code used the old timer API here] Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
2020-05-22padata: ensure padata_do_serial() runs on the correct CPUMathias Krause
commit 350ef88e7e922354f82a931897ad4a4ce6c686ff upstream. If the algorithm we're parallelizing is asynchronous we might change CPUs between padata_do_parallel() and padata_do_serial(). However, we don't expect this to happen as we need to enqueue the padata object into the per-cpu reorder queue we took it from, i.e. the same-cpu's parallel queue. Ensure we're not switching CPUs for a given padata object by tracking the CPU within the padata object. If the serial callback gets called on the wrong CPU, defer invoking padata_reorder() via a kernel worker on the CPU we're expected to run on. Signed-off-by: Mathias Krause <minipli@googlemail.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
2020-05-22padata: ensure the reorder timer callback runs on the correct CPUMathias Krause
commit cf5868c8a22dc2854b96e9569064bb92365549ca upstream. The reorder timer function runs on the CPU where the timer interrupt was handled which is not necessarily one of the CPUs of the 'pcpu' CPU mask set. Ensure the padata_reorder() callback runs on the correct CPU, which is one in the 'pcpu' CPU mask set and, preferrably, the next expected one. Do so by comparing the current CPU with the expected target CPU. If they match, call padata_reorder() right away. If they differ, schedule a work item on the target CPU that does the padata_reorder() call for us. Signed-off-by: Mathias Krause <minipli@googlemail.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
2020-05-22padata: set cpu_index of unused CPUs to -1Mathias Krause
commit 1bd845bcb41d5b7f83745e0cb99273eb376f2ec5 upstream. The parallel queue per-cpu data structure gets initialized only for CPUs in the 'pcpu' CPU mask set. This is not sufficient as the reorder timer may run on a different CPU and might wrongly decide it's the target CPU for the next reorder item as per-cpu memory gets memset(0) and we might be waiting for the first CPU in cpumask.pcpu, i.e. cpu_index 0. Make the '__this_cpu_read(pd->pqueue->cpu_index) == next_queue->cpu_index' compare in padata_get_next() fail in this case by initializing the cpu_index member of all per-cpu parallel queues. Use -1 for unused ones. Signed-off-by: Mathias Krause <minipli@googlemail.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
2020-05-22padata: get_next is never NULLJason A. Donenfeld
commit 69b348449bda0f9588737539cfe135774c9939a7 upstream. Per Dan's static checker warning, the code that returns NULL was removed in 2010, so this patch updates the comments and fixes the code assumptions. Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com> Reported-by: Dan Carpenter <dan.carpenter@oracle.com> Acked-by: Steffen Klassert <steffen.klassert@secunet.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
2020-05-22padata: avoid race in reorderingJason A. Donenfeld
commit de5540d088fe97ad583cc7d396586437b32149a5 upstream. Under extremely heavy uses of padata, crashes occur, and with list debugging turned on, this happens instead: [87487.298728] WARNING: CPU: 1 PID: 882 at lib/list_debug.c:33 __list_add+0xae/0x130 [87487.301868] list_add corruption. prev->next should be next (ffffb17abfc043d0), but was ffff8dba70872c80. (prev=ffff8dba70872b00). [87487.339011] [<ffffffff9a53d075>] dump_stack+0x68/0xa3 [87487.342198] [<ffffffff99e119a1>] ? console_unlock+0x281/0x6d0 [87487.345364] [<ffffffff99d6b91f>] __warn+0xff/0x140 [87487.348513] [<ffffffff99d6b9aa>] warn_slowpath_fmt+0x4a/0x50 [87487.351659] [<ffffffff9a58b5de>] __list_add+0xae/0x130 [87487.354772] [<ffffffff9add5094>] ? _raw_spin_lock+0x64/0x70 [87487.357915] [<ffffffff99eefd66>] padata_reorder+0x1e6/0x420 [87487.361084] [<ffffffff99ef0055>] padata_do_serial+0xa5/0x120 padata_reorder calls list_add_tail with the list to which its adding locked, which seems correct: spin_lock(&squeue->serial.lock); list_add_tail(&padata->list, &squeue->serial.list); spin_unlock(&squeue->serial.lock); This therefore leaves only place where such inconsistency could occur: if padata->list is added at the same time on two different threads. This pdata pointer comes from the function call to padata_get_next(pd), which has in it the following block: next_queue = per_cpu_ptr(pd->pqueue, cpu); padata = NULL; reorder = &next_queue->reorder; if (!list_empty(&reorder->list)) { padata = list_entry(reorder->list.next, struct padata_priv, list); spin_lock(&reorder->lock); list_del_init(&padata->list); atomic_dec(&pd->reorder_objects); spin_unlock(&reorder->lock); pd->processed++; goto out; } out: return padata; I strongly suspect that the problem here is that two threads can race on reorder list. Even though the deletion is locked, call to list_entry is not locked, which means it's feasible that two threads pick up the same padata object and subsequently call list_add_tail on them at the same time. The fix is thus be hoist that lock outside of that block. Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com> Acked-by: Steffen Klassert <steffen.klassert@secunet.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
2020-05-22padata: Remove unused but set variablesTobias Klauser
commit 119a0798dc42ed4c4f96d39b8b676efcea73aec6 upstream. Remove the unused but set variable pinst in padata_parallel_worker to fix the following warning when building with 'W=1': kernel/padata.c: In function ‘padata_parallel_worker’: kernel/padata.c:68:26: warning: variable ‘pinst’ set but not used [-Wunused-but-set-variable] Also remove the now unused variable pd which is only used to set pinst. Signed-off-by: Tobias Klauser <tklauser@distanz.ch> Acked-by: Steffen Klassert <steffen.klassert@secunet.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
2020-04-28futex: Unbreak futex hashingThomas Gleixner
commit 8d67743653dce5a0e7aa500fcccb237cde7ad88e upstream. The recent futex inode life time fix changed the ordering of the futex key union struct members, but forgot to adjust the hash function accordingly, As a result the hashing omits the leading 64bit and even hashes beyond the futex key causing a bad hash distribution which led to a ~100% performance regression. Hand in the futex key pointer instead of a random struct member and make the size calculation based of the struct offset. Fixes: 8019ad13ef7f ("futex: Fix inode life-time issue") Reported-by: Rong Chen <rong.a.chen@intel.com> Decoded-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Rong Chen <rong.a.chen@intel.com> Link: https://lkml.kernel.org/r/87h7yy90ve.fsf@nanos.tec.linutronix.de Signed-off-by: Ben Hutchings <ben@decadent.org.uk> Cc: Jann Horn <jannh@google.com>
2020-04-28futex: Fix inode life-time issuePeter Zijlstra
commit 8019ad13ef7f64be44d4f892af9c840179009254 upstream. As reported by Jann, ihold() does not in fact guarantee inode persistence. And instead of making it so, replace the usage of inode pointers with a per boot, machine wide, unique inode identifier. This sequence number is global, but shared (file backed) futexes are rare enough that this should not become a performance issue. Reported-by: Jann Horn <jannh@google.com> Suggested-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> [bwh: Backported to 3.16: Use atomic64_cmpxchg() instead of the _relaxed() variant which we don't have] Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
2020-04-28ptp: fix the race between the release of ptp_clock and cdevVladis Dronov
commit a33121e5487b424339636b25c35d3a180eaa5f5e upstream. In a case when a ptp chardev (like /dev/ptp0) is open but an underlying device is removed, closing this file leads to a race. This reproduces easily in a kvm virtual machine: ts# cat openptp0.c int main() { ... fp = fopen("/dev/ptp0", "r"); ... sleep(10); } ts# uname -r 5.5.0-rc3-46cf053e ts# cat /proc/cmdline ... slub_debug=FZP ts# modprobe ptp_kvm ts# ./openptp0 & [1] 670 opened /dev/ptp0, sleeping 10s... ts# rmmod ptp_kvm ts# ls /dev/ptp* ls: cannot access '/dev/ptp*': No such file or directory ts# ...woken up [ 48.010809] general protection fault: 0000 [#1] SMP [ 48.012502] CPU: 6 PID: 658 Comm: openptp0 Not tainted 5.5.0-rc3-46cf053e #25 [ 48.014624] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), ... [ 48.016270] RIP: 0010:module_put.part.0+0x7/0x80 [ 48.017939] RSP: 0018:ffffb3850073be00 EFLAGS: 00010202 [ 48.018339] RAX: 000000006b6b6b6b RBX: 6b6b6b6b6b6b6b6b RCX: ffff89a476c00ad0 [ 48.018936] RDX: fffff65a08d3ea08 RSI: 0000000000000247 RDI: 6b6b6b6b6b6b6b6b [ 48.019470] ... ^^^ a slub poison [ 48.023854] Call Trace: [ 48.024050] __fput+0x21f/0x240 [ 48.024288] task_work_run+0x79/0x90 [ 48.024555] do_exit+0x2af/0xab0 [ 48.024799] ? vfs_write+0x16a/0x190 [ 48.025082] do_group_exit+0x35/0x90 [ 48.025387] __x64_sys_exit_group+0xf/0x10 [ 48.025737] do_syscall_64+0x3d/0x130 [ 48.026056] entry_SYSCALL_64_after_hwframe+0x44/0xa9 [ 48.026479] RIP: 0033:0x7f53b12082f6 [ 48.026792] ... [ 48.030945] Modules linked in: ptp i6300esb watchdog [last unloaded: ptp_kvm] [ 48.045001] Fixing recursive fault but reboot is needed! This happens in: static void __fput(struct file *file) { ... if (file->f_op->release) file->f_op->release(inode, file); <<< cdev is kfree'd here if (unlikely(S_ISCHR(inode->i_mode) && inode->i_cdev != NULL && !(mode & FMODE_PATH))) { cdev_put(inode->i_cdev); <<< cdev fields are accessed here Namely: __fput() posix_clock_release() kref_put(&clk->kref, delete_clock) <<< the last reference delete_clock() delete_ptp_clock() kfree(ptp) <<< cdev is embedded in ptp cdev_put module_put(p->owner) <<< *p is kfree'd, bang! Here cdev is embedded in posix_clock which is embedded in ptp_clock. The race happens because ptp_clock's lifetime is controlled by two refcounts: kref and cdev.kobj in posix_clock. This is wrong. Make ptp_clock's sysfs device a parent of cdev with cdev_device_add() created especially for such cases. This way the parent device with its ptp_clock is not released until all references to the cdev are released. This adds a requirement that an initialized but not exposed struct device should be provided to posix_clock_register() by a caller instead of a simple dev_t. This approach was adopted from the commit 72139dfa2464 ("watchdog: Fix the race between the release of watchdog_core_data and cdev"). See details of the implementation in the commit 233ed09d7fda ("chardev: add helper function to register char devs with a struct device"). Link: https://lore.kernel.org/linux-fsdevel/20191125125342.6189-1-vdronov@redhat.com/T/#u Analyzed-by: Stephen Johnston <sjohnsto@redhat.com> Analyzed-by: Vern Lovejoy <vlovejoy@redhat.com> Signed-off-by: Vladis Dronov <vdronov@redhat.com> Acked-by: Richard Cochran <richardcochran@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
2020-04-28blktrace: fix dereference after null checkCengiz Can
commit 153031a301bb07194e9c37466cfce8eacb977621 upstream. There was a recent change in blktrace.c that added a RCU protection to `q->blk_trace` in order to fix a use-after-free issue during access. However the change missed an edge case that can lead to dereferencing of `bt` pointer even when it's NULL: Coverity static analyzer marked this as a FORWARD_NULL issue with CID 1460458. ``` /kernel/trace/blktrace.c: 1904 in sysfs_blk_trace_attr_store() 1898 ret = 0; 1899 if (bt == NULL) 1900 ret = blk_trace_setup_queue(q, bdev); 1901 1902 if (ret == 0) { 1903 if (attr == &dev_attr_act_mask) >>> CID 1460458: Null pointer dereferences (FORWARD_NULL) >>> Dereferencing null pointer "bt". 1904 bt->act_mask = value; 1905 else if (attr == &dev_attr_pid) 1906 bt->pid = value; 1907 else if (attr == &dev_attr_start_lba) 1908 bt->start_lba = value; 1909 else if (attr == &dev_attr_end_lba) ``` Added a reassignment with RCU annotation to fix the issue. Fixes: c780e86dd48 ("blktrace: Protect q->blk_trace with RCU") Reviewed-by: Ming Lei <ming.lei@redhat.com> Reviewed-by: Bob Liu <bob.liu@oracle.com> Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Cengiz Can <cengiz@kernel.wtf> Signed-off-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
2020-04-28blktrace: Protect q->blk_trace with RCUJan Kara
commit c780e86dd48ef6467a1146cf7d0fe1e05a635039 upstream. KASAN is reporting that __blk_add_trace() has a use-after-free issue when accessing q->blk_trace. Indeed the switching of block tracing (and thus eventual freeing of q->blk_trace) is completely unsynchronized with the currently running tracing and thus it can happen that the blk_trace structure is being freed just while __blk_add_trace() works on it. Protect accesses to q->blk_trace by RCU during tracing and make sure we wait for the end of RCU grace period when shutting down tracing. Luckily that is rare enough event that we can afford that. Note that postponing the freeing of blk_trace to an RCU callback should better be avoided as it could have unexpected user visible side-effects as debugfs files would be still existing for a short while block tracing has been shut down. Link: https://bugzilla.kernel.org/show_bug.cgi?id=205711 Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com> Reviewed-by: Ming Lei <ming.lei@redhat.com> Tested-by: Ming Lei <ming.lei@redhat.com> Reviewed-by: Bart Van Assche <bvanassche@acm.org> Reported-by: Tristan Madani <tristmd@gmail.com> Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <axboe@kernel.dk> [bwh: Backported to 3.16: - Drop changes in blk_trace_note_message_enabled(), blk_trace_bio_get_cgid() - Adjust context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
2020-04-28blktrace: re-write setting q->blk_traceDavidlohr Bueso
commit cdea01b2bf98affb7e9c44530108a4a28535eee8 upstream. This is really about simplifying the double xchg patterns into a single cmpxchg, with the same logic. Other than the immediate cleanup, there are some subtleties this change deals with: (i) While the load of the old bt is fully ordered wrt everything, ie: old_bt = xchg(&q->blk_trace, bt); [barrier] if (old_bt) (void) xchg(&q->blk_trace, old_bt); [barrier] blk_trace could still be changed between the xchg and the old_bt load. Note that this description is merely theoretical and afaict very small, but doing everything in a single context with cmpxchg closes this potential race. (ii) Ordering guarantees are obviously kept with cmpxchg. (iii) Gets rid of the hacky-by-nature (void)xchg pattern. Signed-off-by: Davidlohr Bueso <dbueso@suse.de> eviewed-by: Jeff Moyer <jmoyer@redhat.com> Signed-off-by: Jens Axboe <axboe@fb.com> Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
2020-04-28namei: allow restricted O_CREAT of FIFOs and regular filesSalvatore Mesoraca
commit 30aba6656f61ed44cba445a3c0d38b296fa9e8f5 upstream. Disallows open of FIFOs or regular files not owned by the user in world writable sticky directories, unless the owner is the same as that of the directory or the file is opened without the O_CREAT flag. The purpose is to make data spoofing attacks harder. This protection can be turned on and off separately for FIFOs and regular files via sysctl, just like the symlinks/hardlinks protection. This patch is based on Openwall's "HARDEN_FIFO" feature by Solar Designer. This is a brief list of old vulnerabilities that could have been prevented by this feature, some of them even allow for privilege escalation: CVE-2000-1134 CVE-2007-3852 CVE-2008-0525 CVE-2009-0416 CVE-2011-4834 CVE-2015-1838 CVE-2015-7442 CVE-2016-7489 This list is not meant to be complete. It's difficult to track down all vulnerabilities of this kind because they were often reported without any mention of this particular attack vector. In fact, before hardlinks/symlinks restrictions, fifos/regular files weren't the favorite vehicle to exploit them. [s.mesoraca16@gmail.com: fix bug reported by Dan Carpenter] Link: https://lkml.kernel.org/r/20180426081456.GA7060@mwanda Link: http://lkml.kernel.org/r/1524829819-11275-1-git-send-email-s.mesoraca16@gmail.com [keescook@chromium.org: drop pr_warn_ratelimited() in favor of audit changes in the future] [keescook@chromium.org: adjust commit subjet] Link: http://lkml.kernel.org/r/20180416175918.GA13494@beast Signed-off-by: Salvatore Mesoraca <s.mesoraca16@gmail.com> Signed-off-by: Kees Cook <keescook@chromium.org> Suggested-by: Solar Designer <solar@openwall.com> Suggested-by: Kees Cook <keescook@chromium.org> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
2020-04-28kernel/trace: Fix do not unregister tracepoints when register ↵Kaitao Cheng
sched_migrate_task fail commit 50f9ad607ea891a9308e67b81f774c71736d1098 upstream. In the function, if register_trace_sched_migrate_task() returns error, sched_switch/sched_wakeup_new/sched_wakeup won't unregister. That is why fail_deprobe_sched_switch was added. Link: http://lkml.kernel.org/r/20191231133530.2794-1-pilgrimtao@gmail.com Fixes: 478142c39c8c2 ("tracing: do not grab lock in wakeup latency function tracing") Signed-off-by: Kaitao Cheng <pilgrimtao@gmail.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
2020-04-28ftrace: Avoid potential division by zero in function profilerWen Yang
commit e31f7939c1c27faa5d0e3f14519eaf7c89e8a69d upstream. The ftrace_profile->counter is unsigned long and do_div truncates it to 32 bits, which means it can test non-zero and be truncated to zero for division. Fix this issue by using div64_ul() instead. Link: http://lkml.kernel.org/r/20200103030248.14516-1-wenyang@linux.alibaba.com Fixes: e330b3bcd8319 ("tracing: Show sample std dev in function profiling") Fixes: 34886c8bc590f ("tracing: add average time in function to function profiler") Signed-off-by: Wen Yang <wenyang@linux.alibaba.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
2020-04-28tracing: Have stack tracer compile when MCOUNT_INSN_SIZE is not definedSteven Rostedt (VMware)
commit b8299d362d0837ae39e87e9019ebe6b736e0f035 upstream. On some archs with some configurations, MCOUNT_INSN_SIZE is not defined, and this makes the stack tracer fail to compile. Just define it to zero in this case. Link: https://lore.kernel.org/r/202001020219.zvE3vsty%lkp@intel.com Fixes: 4df297129f622 ("tracing: Remove most or all of stack tracer stack size from stack_max_size") Reported-by: kbuild test robot <lkp@intel.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
2020-04-28taskstats: fix data-raceChristian Brauner
commit 0b8d616fb5a8ffa307b1d3af37f55c15dae14f28 upstream. When assiging and testing taskstats in taskstats_exit() there's a race when setting up and reading sig->stats when a thread-group with more than one thread exits: write to 0xffff8881157bbe10 of 8 bytes by task 7951 on cpu 0: taskstats_tgid_alloc kernel/taskstats.c:567 [inline] taskstats_exit+0x6b7/0x717 kernel/taskstats.c:596 do_exit+0x2c2/0x18e0 kernel/exit.c:864 do_group_exit+0xb4/0x1c0 kernel/exit.c:983 get_signal+0x2a2/0x1320 kernel/signal.c:2734 do_signal+0x3b/0xc00 arch/x86/kernel/signal.c:815 exit_to_usermode_loop+0x250/0x2c0 arch/x86/entry/common.c:159 prepare_exit_to_usermode arch/x86/entry/common.c:194 [inline] syscall_return_slowpath arch/x86/entry/common.c:274 [inline] do_syscall_64+0x2d7/0x2f0 arch/x86/entry/common.c:299 entry_SYSCALL_64_after_hwframe+0x44/0xa9 read to 0xffff8881157bbe10 of 8 bytes by task 7949 on cpu 1: taskstats_tgid_alloc kernel/taskstats.c:559 [inline] taskstats_exit+0xb2/0x717 kernel/taskstats.c:596 do_exit+0x2c2/0x18e0 kernel/exit.c:864 do_group_exit+0xb4/0x1c0 kernel/exit.c:983 __do_sys_exit_group kernel/exit.c:994 [inline] __se_sys_exit_group kernel/exit.c:992 [inline] __x64_sys_exit_group+0x2e/0x30 kernel/exit.c:992 do_syscall_64+0xcf/0x2f0 arch/x86/entry/common.c:296 entry_SYSCALL_64_after_hwframe+0x44/0xa9 Fix this by using smp_load_acquire() and smp_store_release(). Reported-by: syzbot+c5d03165a1bd1dead0c1@syzkaller.appspotmail.com Fixes: 34ec12349c8a ("taskstats: cleanup ->signal->stats allocation") Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com> Acked-by: Marco Elver <elver@google.com> Reviewed-by: Will Deacon <will@kernel.org> Reviewed-by: Andrea Parri <parri.andrea@gmail.com> Reviewed-by: Dmitry Vyukov <dvyukov@google.com> Link: https://lore.kernel.org/r/20191009114809.8643-1-christian.brauner@ubuntu.com Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
2020-02-11hrtimer: Get rid of the resolution field in hrtimer_clock_baseThomas Gleixner
commit 398ca17fb54b212cdc9da7ff4a17a35c48dd2103 upstream. The field has no value because all clock bases have the same resolution. The resolution only changes when we switch to high resolution timer mode. We can evaluate that from a single static variable as well. In the !HIGHRES case its simply a constant. Export the variable, so we can simplify the usage sites. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Preeti U Murthy <preeti@linux.vnet.ibm.com> Acked-by: Peter Zijlstra <peterz@infradead.org> Cc: Viresh Kumar <viresh.kumar@linaro.org> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Link: http://lkml.kernel.org/r/20150414203500.645454122@linutronix.de Signed-off-by: Thomas Gleixner <tglx@linutronix.de> [bwh: Backported to 3.16 as dependency of commit 552263456215 "powerpc: Fix vDSO clock_getres()": - Adjust filename, context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
2020-02-11futex: Prevent robust futex exit raceYang Tao
commit ca16d5bee59807bf04deaab0a8eccecd5061528c upstream. Robust futexes utilize the robust_list mechanism to allow the kernel to release futexes which are held when a task exits. The exit can be voluntary or caused by a signal or fault. This prevents that waiters block forever. The futex operations in user space store a pointer to the futex they are either locking or unlocking in the op_pending member of the per task robust list. After a lock operation has succeeded the futex is queued in the robust list linked list and the op_pending pointer is cleared. After an unlock operation has succeeded the futex is removed from the robust list linked list and the op_pending pointer is cleared. The robust list exit code checks for the pending operation and any futex which is queued in the linked list. It carefully checks whether the futex value is the TID of the exiting task. If so, it sets the OWNER_DIED bit and tries to wake up a potential waiter. This is race free for the lock operation but unlock has two race scenarios where waiters might not be woken up. These issues can be observed with regular robust pthread mutexes. PI aware pthread mutexes are not affected. (1) Unlocking task is killed after unlocking the futex value in user space before being able to wake a waiter. pthread_mutex_unlock() | V atomic_exchange_rel (&mutex->__data.__lock, 0) <------------------------killed lll_futex_wake () | | |(__lock = 0) |(enter kernel) | V do_exit() exit_mm() mm_release() exit_robust_list() handle_futex_death() | |(__lock = 0) |(uval = 0) | V if ((uval & FUTEX_TID_MASK) != task_pid_vnr(curr)) return 0; The sanity check which ensures that the user space futex is owned by the exiting task prevents the wakeup of waiters which in consequence block infinitely. (2) Waiting task is killed after a wakeup and before it can acquire the futex in user space. OWNER WAITER futex_wait() pthread_mutex_unlock() | | | |(__lock = 0) | | | V | futex_wake() ------------> wakeup() | |(return to userspace) |(__lock = 0) | V oldval = mutex->__data.__lock <-----------------killed atomic_compare_and_exchange_val_acq (&mutex->__data.__lock, | id | assume_other_futex_waiters, 0) | | | (enter kernel)| | V do_exit() | | V handle_futex_death() | |(__lock = 0) |(uval = 0) | V if ((uval & FUTEX_TID_MASK) != task_pid_vnr(curr)) return 0; The sanity check which ensures that the user space futex is owned by the exiting task prevents the wakeup of waiters, which seems to be correct as the exiting task does not own the futex value, but the consequence is that other waiters wont be woken up and block infinitely. In both scenarios the following conditions are true: - task->robust_list->list_op_pending != NULL - user space futex value == 0 - Regular futex (not PI) If these conditions are met then it is reasonably safe to wake up a potential waiter in order to prevent the above problems. As this might be a false positive it can cause spurious wakeups, but the waiter side has to handle other types of unrelated wakeups, e.g. signals gracefully anyway. So such a spurious wakeup will not affect the correctness of these operations. This workaround must not touch the user space futex value and cannot set the OWNER_DIED bit because the lock value is 0, i.e. uncontended. Setting OWNER_DIED in this case would result in inconsistent state and subsequently in malfunction of the owner died handling in user space. The rest of the user space state is still consistent as no other task can observe the list_op_pending entry in the exiting tasks robust list. The eventually woken up waiter will observe the uncontended lock value and take it over. [ tglx: Massaged changelog and comment. Made the return explicit and not depend on the subsequent check and added constants to hand into handle_futex_death() instead of plain numbers. Fixed a few coding style issues. ] Fixes: 0771dfefc9e5 ("[PATCH] lightweight robust futexes: core") Signed-off-by: Yang Tao <yang.tao172@zte.com.cn> Signed-off-by: Yi Wang <wang.yi59@zte.com.cn> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Ingo Molnar <mingo@kernel.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/1573010582-35297-1-git-send-email-wang.yi59@zte.com.cn Link: https://lkml.kernel.org/r/20191106224555.943191378@linutronix.de [bwh: Backported to 3.16: Implementation is split between futex.c and futex_compat.c, with common definitions in <linux/futex.h>] Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
2020-02-11workqueue: Fix spurious sanity check failures in destroy_workqueue()Tejun Heo
commit def98c84b6cdf2eeea19ec5736e90e316df5206b upstream. Before actually destrying a workqueue, destroy_workqueue() checks whether it's actually idle. If it isn't, it prints out a bunch of warning messages and leaves the workqueue dangling. It unfortunately has a couple issues. * Mayday list queueing increments pwq's refcnts which gets detected as busy and fails the sanity checks. However, because mayday list queueing is asynchronous, this condition can happen without any actual work items left in the workqueue. * Sanity check failure leaves the sysfs interface behind too which can lead to init failure of newer instances of the workqueue. This patch fixes the above two by * If a workqueue has a rescuer, disable and kill the rescuer before sanity checks. Disabling and killing is guaranteed to flush the existing mayday list. * Remove sysfs interface before sanity checks. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Marcin Pawlowski <mpawlowski@fb.com> Reported-by: "Williams, Gerald S" <gerald.s.williams@intel.com> [bwh: Backported to 3.16: destroy_workqueue() also freed wq->rescuer itself] Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
2020-01-11Revert "sched/fair: Fix bandwidth timer clock drift condition"Ben Hutchings
This reverts commit eb29ee5a3873134917a760bf9c416da0a089a0be, which was commit 512ac999d2755d2b7109e996a76b6fb8b888631d upstream. This introduced a regression and doesn't seem to have been suitable for older stable branches. (It has been fixed differently upstream.) Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
2020-01-11PM / Hibernate: Call flush_icache_range() on pages restored in-placeJames Morse
commit f6cf0545ec697ddc278b7457b7d0c0d86a2ea88e upstream. Some architectures require code written to memory as if it were data to be 'cleaned' from any data caches before the processor can fetch them as new instructions. During resume from hibernate, the snapshot code copies some pages directly, meaning these architectures do not get a chance to perform their cache maintenance. Modify the read and decompress code to call flush_icache_range() on all pages that are restored, so that the restored in-place pages are guaranteed to be executable on these architectures. Signed-off-by: James Morse <james.morse@arm.com> Acked-by: Pavel Machek <pavel@ucw.cz> Acked-by: Rafael J. Wysocki <rjw@rjwysocki.net> Acked-by: Catalin Marinas <catalin.marinas@arm.com> [will: make clean_pages_on_* static and remove initialisers] Signed-off-by: Will Deacon <will.deacon@arm.com> Cc: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
2020-01-11suspend: simplify block I/O handlingChristoph Hellwig
commit 343df3c79c62b644ce6ff5dff96c9e0be1ecb242 upstream. Stop abusing struct page functionality and the swap end_io handler, and instead add a modified version of the blk-lib.c bio_batch helpers. Also move the block I/O code into swap.c as they are directly tied into each other. Signed-off-by: Christoph Hellwig <hch@lst.de> Tested-by: Pavel Machek <pavel@ucw.cz> Tested-by: Ming Lin <mlin@kernel.org> Acked-by: Pavel Machek <pavel@ucw.cz> Acked-by: Rafael J. Wysocki <rjw@rjwysocki.net> Signed-off-by: Jens Axboe <axboe@fb.com> [bwh: Backported to 3.16 as dependency of commit f6cf0545ec69 "PM / Hibernate: Call flush_icache_range() on pages restored in-place": - Adjust context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
2020-01-11tracing/uprobes: Fix output for multiple string argumentsAndreas Ziegler
commit 0722069a5374b904ec1a67f91249f90e1cfae259 upstream. When printing multiple uprobe arguments as strings the output for the earlier arguments would also include all later string arguments. This is best explained in an example: Consider adding a uprobe to a function receiving two strings as parameters which is at offset 0xa0 in strlib.so and we want to print both parameters when the uprobe is hit (on x86_64): $ echo 'p:func /lib/strlib.so:0xa0 +0(%di):string +0(%si):string' > \ /sys/kernel/debug/tracing/uprobe_events When the function is called as func("foo", "bar") and we hit the probe, the trace file shows a line like the following: [...] func: (0x7f7e683706a0) arg1="foobar" arg2="bar" Note the extra "bar" printed as part of arg1. This behaviour stacks up for additional string arguments. The strings are stored in a dynamically growing part of the uprobe buffer by fetch_store_string() after copying them from userspace via strncpy_from_user(). The return value of strncpy_from_user() is then directly used as the required size for the string. However, this does not take the terminating null byte into account as the documentation for strncpy_from_user() cleary states that it "[...] returns the length of the string (not including the trailing NUL)" even though the null byte will be copied to the destination. Therefore, subsequent calls to fetch_store_string() will overwrite the terminating null byte of the most recently fetched string with the first character of the current string, leading to the "accumulation" of strings in earlier arguments in the output. Fix this by incrementing the return value of strncpy_from_user() by one if we did not hit the maximum buffer size. Link: http://lkml.kernel.org/r/20190116141629.5752-1-andreas.ziegler@fau.de Cc: Ingo Molnar <mingo@redhat.com> Fixes: 5baaa59ef09e ("tracing/probes: Implement 'memory' fetch method for uprobes") Acked-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Andreas Ziegler <andreas.ziegler@fau.de> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
2019-12-19tracing: Get trace_array reference for available_tracers filesSteven Rostedt (VMware)
commit 194c2c74f5532e62c218adeb8e2b683119503907 upstream. As instances may have different tracers available, we need to look at the trace_array descriptor that shows the list of the available tracers for the instance. But there's a race between opening the file and an admin deleting the instance. The trace_array_get() needs to be called before accessing the trace_array. Fixes: 607e2ea167e56 ("tracing: Set up infrastructure to allow tracers for instances") Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
2019-12-19sched/fair: Scale bandwidth quota and period without losing quota/period ↵Xuewei Zhang
ratio precision commit 4929a4e6faa0f13289a67cae98139e727f0d4a97 upstream. The quota/period ratio is used to ensure a child task group won't get more bandwidth than the parent task group, and is calculated as: normalized_cfs_quota() = [(quota_us << 20) / period_us] If the quota/period ratio was changed during this scaling due to precision loss, it will cause inconsistency between parent and child task groups. See below example: A userspace container manager (kubelet) does three operations: 1) Create a parent cgroup, set quota to 1,000us and period to 10,000us. 2) Create a few children cgroups. 3) Set quota to 1,000us and period to 10,000us on a child cgroup. These operations are expected to succeed. However, if the scaling of 147/128 happens before step 3, quota and period of the parent cgroup will be changed: new_quota: 1148437ns, 1148us new_period: 11484375ns, 11484us And when step 3 comes in, the ratio of the child cgroup will be 104857, which will be larger than the parent cgroup ratio (104821), and will fail. Scaling them by a factor of 2 will fix the problem. Tested-by: Phil Auld <pauld@redhat.com> Signed-off-by: Xuewei Zhang <xueweiz@google.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Phil Auld <pauld@redhat.com> Cc: Anton Blanchard <anton@ozlabs.org> Cc: Ben Segall <bsegall@google.com> Cc: Dietmar Eggemann <dietmar.eggemann@arm.com> Cc: Juri Lelli <juri.lelli@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mel Gorman <mgorman@suse.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vincent Guittot <vincent.guittot@linaro.org> Fixes: 2e8e19226398 ("sched/fair: Limit sched_cfs_period_timer() loop to avoid hard lockup") Link: https://lkml.kernel.org/r/20191004001243.140897-1-xueweiz@google.com Signed-off-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
2019-12-19panic: ensure preemption is disabled during panic()Will Deacon
commit 20bb759a66be52cf4a9ddd17fddaf509e11490cd upstream. Calling 'panic()' on a kernel with CONFIG_PREEMPT=y can leave the calling CPU in an infinite loop, but with interrupts and preemption enabled. From this state, userspace can continue to be scheduled, despite the system being "dead" as far as the kernel is concerned. This is easily reproducible on arm64 when booting with "nosmp" on the command line; a couple of shell scripts print out a periodic "Ping" message whilst another triggers a crash by writing to /proc/sysrq-trigger: | sysrq: Trigger a crash | Kernel panic - not syncing: sysrq triggered crash | CPU: 0 PID: 1 Comm: init Not tainted 5.2.15 #1 | Hardware name: linux,dummy-virt (DT) | Call trace: | dump_backtrace+0x0/0x148 | show_stack+0x14/0x20 | dump_stack+0xa0/0xc4 | panic+0x140/0x32c | sysrq_handle_reboot+0x0/0x20 | __handle_sysrq+0x124/0x190 | write_sysrq_trigger+0x64/0x88 | proc_reg_write+0x60/0xa8 | __vfs_write+0x18/0x40 | vfs_write+0xa4/0x1b8 | ksys_write+0x64/0xf0 | __arm64_sys_write+0x14/0x20 | el0_svc_common.constprop.0+0xb0/0x168 | el0_svc_handler+0x28/0x78 | el0_svc+0x8/0xc | Kernel Offset: disabled | CPU features: 0x0002,24002004 | Memory Limit: none | ---[ end Kernel panic - not syncing: sysrq triggered crash ]--- | Ping 2! | Ping 1! | Ping 1! | Ping 2! The issue can also be triggered on x86 kernels if CONFIG_SMP=n, otherwise local interrupts are disabled in 'smp_send_stop()'. Disable preemption in 'panic()' before re-enabling interrupts. Link: http://lkml.kernel.org/r/20191002123538.22609-1-will@kernel.org Link: https://lore.kernel.org/r/BX1W47JXPMR8.58IYW53H6M5N@dragonstone Signed-off-by: Will Deacon <will@kernel.org> Reported-by: Xogium <contact@xogium.me> Reviewed-by: Kees Cook <keescook@chromium.org> Cc: Russell King <linux@armlinux.org.uk> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Petr Mladek <pmladek@suse.com> Cc: Feng Tang <feng.tang@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
2019-12-19tick: broadcast-hrtimer: Fix a race in bc_set_nextBalasubramani Vivekanandan
commit b9023b91dd020ad7e093baa5122b6968c48cc9e0 upstream. When a cpu requests broadcasting, before starting the tick broadcast hrtimer, bc_set_next() checks if the timer callback (bc_handler) is active using hrtimer_try_to_cancel(). But hrtimer_try_to_cancel() does not provide the required synchronization when the callback is active on other core. The callback could have already executed tick_handle_oneshot_broadcast() and could have also returned. But still there is a small time window where the hrtimer_try_to_cancel() returns -1. In that case bc_set_next() returns without doing anything, but the next_event of the tick broadcast clock device is already set to a timeout value. In the race condition diagram below, CPU #1 is running the timer callback and CPU #2 is entering idle state and so calls bc_set_next(). In the worst case, the next_event will contain an expiry time, but the hrtimer will not be started which happens when the racing callback returns HRTIMER_NORESTART. The hrtimer might never recover if all further requests from the CPUs to subscribe to tick broadcast have timeout greater than the next_event of tick broadcast clock device. This leads to cascading of failures and finally noticed as rcu stall warnings Here is a depiction of the race condition CPU #1 (Running timer callback) CPU #2 (Enter idle and subscribe to tick broadcast) --------------------- --------------------- __run_hrtimer() tick_broadcast_enter() bc_handler() __tick_broadcast_oneshot_control() tick_handle_oneshot_broadcast() raw_spin_lock(&tick_broadcast_lock); dev->next_event = KTIME_MAX; //wait for tick_broadcast_lock //next_event for tick broadcast clock set to KTIME_MAX since no other cores subscribed to tick broadcasting raw_spin_unlock(&tick_broadcast_lock); if (dev->next_event == KTIME_MAX) return HRTIMER_NORESTART // callback function exits without restarting the hrtimer //tick_broadcast_lock acquired raw_spin_lock(&tick_broadcast_lock); tick_broadcast_set_event() clockevents_program_event() dev->next_event = expires; bc_set_next() hrtimer_try_to_cancel() //returns -1 since the timer callback is active. Exits without restarting the timer cpu_base->running = NULL; The comment that hrtimer cannot be armed from within the callback is wrong. It is fine to start the hrtimer from within the callback. Also it is safe to start the hrtimer from the enter/exit idle code while the broadcast handler is active. The enter/exit idle code and the broadcast handler are synchronized using tick_broadcast_lock. So there is no need for the existing try to cancel logic. All this can be removed which will eliminate the race condition as well. Fixes: 5d1638acb9f6 ("tick: Introduce hrtimer based broadcast") Originally-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Balasubramani Vivekanandan <balasubramani_vivekanandan@mentor.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lkml.kernel.org/r/20190926135101.12102-2-balasubramani_vivekanandan@mentor.com [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
2019-12-19tick: hrtimer-broadcast: Prevent endless restarting when broadcast device is ↵Andreas Sandberg
unused commit 38d23a6cc16c02f7b0c920266053f340b5601735 upstream. The hrtimer callback in the hrtimer's tick broadcast code sometimes incorrectly ends up scheduling events at the current tick causing the kernel to hang servicing the same hrtimer forever. This typically happens when a device is swapped out by tick_install_broadcast_device(), which replaces the event handler with clock_events_handle_noop() and sets the device mode to CLOCK_EVT_MODE_UNUSED. If the timer is scheduled when this happens, the next_event field will not be updated and the hrtimer ends up being restarted at the current tick. To prevent this from happening, only try to restart the hrtimer if the broadcast clock event device is in one of the active modes and try to cancel the timer when entering the CLOCK_EVT_MODE_UNUSED mode. Signed-off-by: Andreas Sandberg <andreas.sandberg@arm.com> Tested-by: Catalin Marinas <catalin.marinas@arm.com> Acked-by: Mark Rutland <mark.rutland@arm.com> Reviewed-by: Preeti U Murthy <preeti@linux.vnet.ibm.com> Link: http://lkml.kernel.org/r/1429880765-5558-1-git-send-email-andreas.sandberg@arm.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de> [bwh: Backported to 3.16 as dependency of commit b9023b91dd02 "tick: broadcast-hrtimer: Fix a race in bc_set_next"] Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
2019-12-19tick: broadcast-hrtimer: Remove overly clever return value abuseThomas Gleixner
commit b8a62f1ff0ccb18fdc25c6150d1cd394610f4753 upstream. The assignment of bc_moved in the conditional construct relies on the fact that in the case of hrtimer_start() invocation the return value is always 0. It took me a while to understand it. We want to get rid of the hrtimer_start() return value. Open code the logic which makes it readable as well. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Preeti U Murthy <preeti@linux.vnet.ibm.com> Acked-by: Peter Zijlstra <peterz@infradead.org> Cc: Viresh Kumar <viresh.kumar@linaro.org> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Link: http://lkml.kernel.org/r/20150414203503.404751457@linutronix.de Signed-off-by: Thomas Gleixner <tglx@linutronix.de> [bwh: Backported to 3.16 to ease backporting commit b9023b91dd02 "tick: broadcast-hrtimer: Fix a race in bc_set_next"] Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
2019-12-19hrtimer: Store cpu-number in struct hrtimer_cpu_baseViresh Kumar
commit cddd02489f52ccf635ed65931214729a23b93cd6 upstream. In lowres mode, hrtimers are serviced by the tick instead of a clock event. Now it works well as long as the tick stays periodic but we must also make sure that the hrtimers are serviced in dynticks mode. Part of that job consist in kicking a dynticks hrtimer target in order to make it reconsider the next tick to schedule to correctly handle the hrtimer's expiring time. And that part isn't handled by the hrtimers subsystem. To prepare for fixing this, we need __hrtimer_start_range_ns() to be able to resolve the CPU target associated to a hrtimer's object 'cpu_base' so that the kick can be centralized there. So lets store it in the 'struct hrtimer_cpu_base' to resolve the CPU without overhead. It is set once at CPU's online notification. Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Link: http://lkml.kernel.org/r/1403393357-2070-4-git-send-email-fweisbec@gmail.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de> [bwh: Backported to 3.16 as dependency of commit b9023b91dd02 "tick: broadcast-hrtimer: Fix a race in bc_set_next": - Adjust filename, context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
2019-11-22alarmtimer: Use EOPNOTSUPP instead of ENOTSUPPThadeu Lima de Souza Cascardo
commit f18ddc13af981ce3c7b7f26925f099e7c6929aba upstream. ENOTSUPP is not supposed to be returned to userspace. This was found on an OpenPower machine, where the RTC does not support set_alarm. On that system, a clock_nanosleep(CLOCK_REALTIME_ALARM, ...) results in "524 Unknown error 524" Replace it with EOPNOTSUPP which results in the expected "95 Operation not supported" error. Fixes: 1c6b39ad3f01 (alarmtimers: Return -ENOTSUPP if no RTC device is present) Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lkml.kernel.org/r/20190903171802.28314-1-cascardo@canonical.com [ pvorel: backport for v3.16, changes also in alarm_timer_{del,set}(), which were removed in f2c45807d3992fe0f173f34af9c347d907c31686 in v4.13-rc1 ] Signed-off-by: Petr Vorel <pvorel@suse.cz> Acked-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com> Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
2019-11-22genirq: Prevent NULL pointer dereference in resend_irqs()Yunfeng Ye
commit eddf3e9c7c7e4d0707c68d1bb22cc6ec8aef7d4a upstream. The following crash was observed: Unable to handle kernel NULL pointer dereference at 0000000000000158 Internal error: Oops: 96000004 [#1] SMP pc : resend_irqs+0x68/0xb0 lr : resend_irqs+0x64/0xb0 ... Call trace: resend_irqs+0x68/0xb0 tasklet_action_common.isra.6+0x84/0x138 tasklet_action+0x2c/0x38 __do_softirq+0x120/0x324 run_ksoftirqd+0x44/0x60 smpboot_thread_fn+0x1ac/0x1e8 kthread+0x134/0x138 ret_from_fork+0x10/0x18 The reason for this is that the interrupt resend mechanism happens in soft interrupt context, which is a asynchronous mechanism versus other operations on interrupts. free_irq() does not take resend handling into account. Thus, the irq descriptor might be already freed before the resend tasklet is executed. resend_irqs() does not check the return value of the interrupt descriptor lookup and derefences the return value unconditionally. 1): __setup_irq irq_startup check_irq_resend // activate softirq to handle resend irq 2): irq_domain_free_irqs irq_free_descs free_desc call_rcu(&desc->rcu, delayed_free_desc) 3): __do_softirq tasklet_action resend_irqs desc = irq_to_desc(irq) desc->handle_irq(desc) // desc is NULL --> Ooops Fix this by adding a NULL pointer check in resend_irqs() before derefencing the irq descriptor. Fixes: a4633adcdbc1 ("[PATCH] genirq: add genirq sw IRQ-retrigger") Signed-off-by: Yunfeng Ye <yeyunfeng@huawei.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Zhiqiang Liu <liuzhiqiang26@huawei.com> Link: https://lkml.kernel.org/r/1630ae13-5c8e-901e-de09-e740b6a426a7@huawei.com Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
2019-11-22sched/fair: Don't assign runtime for throttled cfs_rqLiangyan
commit 5e2d2cc2588bd3307ce3937acbc2ed03c830a861 upstream. do_sched_cfs_period_timer() will refill cfs_b runtime and call distribute_cfs_runtime to unthrottle cfs_rq, sometimes cfs_b->runtime will allocate all quota to one cfs_rq incorrectly, then other cfs_rqs attached to this cfs_b can't get runtime and will be throttled. We find that one throttled cfs_rq has non-negative cfs_rq->runtime_remaining and cause an unexpetced cast from s64 to u64 in snippet: distribute_cfs_runtime() { runtime = -cfs_rq->runtime_remaining + 1; } The runtime here will change to a large number and consume all cfs_b->runtime in this cfs_b period. According to Ben Segall, the throttled cfs_rq can have account_cfs_rq_runtime called on it because it is throttled before idle_balance, and the idle_balance calls update_rq_clock to add time that is accounted to the task. This commit prevents cfs_rq to be assgined new runtime if it has been throttled until that distribute_cfs_runtime is called. Signed-off-by: Liangyan <liangyan.peng@linux.alibaba.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Valentin Schneider <valentin.schneider@arm.com> Reviewed-by: Ben Segall <bsegall@google.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: shanpeic@linux.alibaba.com Cc: xlpang@linux.alibaba.com Fixes: d3d9dc330236 ("sched: Throttle entities exceeding their allowed bandwidth") Link: https://lkml.kernel.org/r/20190826121633.6538-1-liangyan.peng@linux.alibaba.com Signed-off-by: Ingo Molnar <mingo@kernel.org> [bwh: Backported to 3.16: Open-code SCHED_WARN_ON().] Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
2019-11-22sched/fair: Don't free p->numa_faults with concurrent readersJann Horn
commit 16d51a590a8ce3befb1308e0e7ab77f3b661af33 upstream. When going through execve(), zero out the NUMA fault statistics instead of freeing them. During execve, the task is reachable through procfs and the scheduler. A concurrent /proc/*/sched reader can read data from a freed ->numa_faults allocation (confirmed by KASAN) and write it back to userspace. I believe that it would also be possible for a use-after-free read to occur through a race between a NUMA fault and execve(): task_numa_fault() can lead to task_numa_compare(), which invokes task_weight() on the currently running task of a different CPU. Another way to fix this would be to make ->numa_faults RCU-managed or add extra locking, but it seems easier to wipe the NUMA fault statistics on execve. Signed-off-by: Jann Horn <jannh@google.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Petr Mladek <pmladek@suse.com> Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Will Deacon <will@kernel.org> Fixes: 82727018b0d3 ("sched/numa: Call task_numa_free() from do_execve()") Link: https://lkml.kernel.org/r/20190716152047.14424-1-jannh@google.com Signed-off-by: Ingo Molnar <mingo@kernel.org> [bwh: Backported to 3.16: adjust filename, context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
2019-10-31padata: use smp_mb in padata_reorder to avoid orphaned padata jobsDaniel Jordan
commit cf144f81a99d1a3928f90b0936accfd3f45c9a0a upstream. Testing padata with the tcrypt module on a 5.2 kernel... # modprobe tcrypt alg="pcrypt(rfc4106(gcm(aes)))" type=3 # modprobe tcrypt mode=211 sec=1 ...produces this splat: INFO: task modprobe:10075 blocked for more than 120 seconds. Not tainted 5.2.0-base+ #16 modprobe D 0 10075 10064 0x80004080 Call Trace: ? __schedule+0x4dd/0x610 ? ring_buffer_unlock_commit+0x23/0x100 schedule+0x6c/0x90 schedule_timeout+0x3b/0x320 ? trace_buffer_unlock_commit_regs+0x4f/0x1f0 wait_for_common+0x160/0x1a0 ? wake_up_q+0x80/0x80 { crypto_wait_req } # entries in braces added by hand { do_one_aead_op } { test_aead_jiffies } test_aead_speed.constprop.17+0x681/0xf30 [tcrypt] do_test+0x4053/0x6a2b [tcrypt] ? 0xffffffffa00f4000 tcrypt_mod_init+0x50/0x1000 [tcrypt] ... The second modprobe command never finishes because in padata_reorder, CPU0's load of reorder_objects is executed before the unlocking store in spin_unlock_bh(pd->lock), causing CPU0 to miss CPU1's increment: CPU0 CPU1 padata_reorder padata_do_serial LOAD reorder_objects // 0 INC reorder_objects // 1 padata_reorder TRYLOCK pd->lock // failed UNLOCK pd->lock CPU0 deletes the timer before returning from padata_reorder and since no other job is submitted to padata, modprobe waits indefinitely. Add a pair of full barriers to guarantee proper ordering: CPU0 CPU1 padata_reorder padata_do_serial UNLOCK pd->lock smp_mb() LOAD reorder_objects INC reorder_objects smp_mb__after_atomic() padata_reorder TRYLOCK pd->lock smp_mb__after_atomic is needed so the read part of the trylock operation comes after the INC, as Andrea points out. Thanks also to Andrea for help with writing a litmus test. Fixes: 16295bec6398 ("padata: Generic parallelization/serialization interface") Signed-off-by: Daniel Jordan <daniel.m.jordan@oracle.com> Cc: Andrea Parri <andrea.parri@amarulasolutions.com> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Herbert Xu <herbert@gondor.apana.org.au> Cc: Paul E. McKenney <paulmck@linux.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steffen Klassert <steffen.klassert@secunet.com> Cc: linux-arch@vger.kernel.org Cc: linux-crypto@vger.kernel.org Cc: linux-kernel@vger.kernel.org Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
2019-10-31signal/pid_namespace: Fix reboot_pid_ns to use send_sig not force_sigEric W. Biederman
commit f9070dc94542093fd516ae4ccea17ef46a4362c5 upstream. The locking in force_sig_info is not prepared to deal with a task that exits or execs (as sighand may change). The is not a locking problem in force_sig as force_sig is only built to handle synchronous exceptions. Further the function force_sig_info changes the signal state if the signal is ignored, or blocked or if SIGNAL_UNKILLABLE will prevent the delivery of the signal. The signal SIGKILL can not be ignored and can not be blocked and SIGNAL_UNKILLABLE won't prevent it from being delivered. So using force_sig rather than send_sig for SIGKILL is confusing and pointless. Because it won't impact the sending of the signal and and because using force_sig is wrong, replace force_sig with send_sig. Cc: Daniel Lezcano <daniel.lezcano@free.fr> Cc: Serge Hallyn <serge@hallyn.com> Cc: Oleg Nesterov <oleg@redhat.com> Fixes: cf3f89214ef6 ("pidns: add reboot_pid_ns() to handle the reboot syscall") Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
2019-10-05tracing/snapshot: Resize spare buffer if size changedEiichi Tsukata
commit 46cc0b44428d0f0e81f11ea98217fc0edfbeab07 upstream. Current snapshot implementation swaps two ring_buffers even though their sizes are different from each other, that can cause an inconsistency between the contents of buffer_size_kb file and the current buffer size. For example: # cat buffer_size_kb 7 (expanded: 1408) # echo 1 > events/enable # grep bytes per_cpu/cpu0/stats bytes: 1441020 # echo 1 > snapshot // current:1408, spare:1408 # echo 123 > buffer_size_kb // current:123, spare:1408 # echo 1 > snapshot // current:1408, spare:123 # grep bytes per_cpu/cpu0/stats bytes: 1443700 # cat buffer_size_kb 123 // != current:1408 And also, a similar per-cpu case hits the following WARNING: Reproducer: # echo 1 > per_cpu/cpu0/snapshot # echo 123 > buffer_size_kb # echo 1 > per_cpu/cpu0/snapshot WARNING: WARNING: CPU: 0 PID: 1946 at kernel/trace/trace.c:1607 update_max_tr_single.part.0+0x2b8/0x380 Modules linked in: CPU: 0 PID: 1946 Comm: bash Not tainted 5.2.0-rc6 #20 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-2.fc30 04/01/2014 RIP: 0010:update_max_tr_single.part.0+0x2b8/0x380 Code: ff e8 dc da f9 ff 0f 0b e9 88 fe ff ff e8 d0 da f9 ff 44 89 ee bf f5 ff ff ff e8 33 dc f9 ff 41 83 fd f5 74 96 e8 b8 da f9 ff <0f> 0b eb 8d e8 af da f9 ff 0f 0b e9 bf fd ff ff e8 a3 da f9 ff 48 RSP: 0018:ffff888063e4fca0 EFLAGS: 00010093 RAX: ffff888066214380 RBX: ffffffff99850fe0 RCX: ffffffff964298a8 RDX: 0000000000000000 RSI: 00000000fffffff5 RDI: 0000000000000005 RBP: 1ffff1100c7c9f96 R08: ffff888066214380 R09: ffffed100c7c9f9b R10: ffffed100c7c9f9a R11: 0000000000000003 R12: 0000000000000000 R13: 00000000ffffffea R14: ffff888066214380 R15: ffffffff99851060 FS: 00007f9f8173c700(0000) GS:ffff88806d000000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000714dc0 CR3: 0000000066fa6000 CR4: 00000000000006f0 Call Trace: ? trace_array_printk_buf+0x140/0x140 ? __mutex_lock_slowpath+0x10/0x10 tracing_snapshot_write+0x4c8/0x7f0 ? trace_printk_init_buffers+0x60/0x60 ? selinux_file_permission+0x3b/0x540 ? tracer_preempt_off+0x38/0x506 ? trace_printk_init_buffers+0x60/0x60 __vfs_write+0x81/0x100 vfs_write+0x1e1/0x560 ksys_write+0x126/0x250 ? __ia32_sys_read+0xb0/0xb0 ? do_syscall_64+0x1f/0x390 do_syscall_64+0xc1/0x390 entry_SYSCALL_64_after_hwframe+0x49/0xbe This patch adds resize_buffer_duplicate_size() to check if there is a difference between current/spare buffer sizes and resize a spare buffer if necessary. Link: http://lkml.kernel.org/r/20190625012910.13109-1-devel@etsukata.com Fixes: ad909e21bbe69 ("tracing: Add internal tracing_snapshot() functions") Signed-off-by: Eiichi Tsukata <devel@etsukata.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
2019-10-05cpu/speculation: Warn on unsupported mitigations= parameterGeert Uytterhoeven
commit 1bf72720281770162c87990697eae1ba2f1d917a upstream. Currently, if the user specifies an unsupported mitigation strategy on the kernel command line, it will be ignored silently. The code will fall back to the default strategy, possibly leaving the system more vulnerable than expected. This may happen due to e.g. a simple typo, or, for a stable kernel release, because not all mitigation strategies have been backported. Inform the user by printing a message. Fixes: 98af8452945c5565 ("cpu/speculation: Add 'mitigations=' cmdline option") Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Jiri Kosina <jkosina@suse.cz> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Ben Hutchings <ben@decadent.org.uk> Link: https://lkml.kernel.org/r/20190516070935.22546-1-geert@linux-m68k.org [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
2019-10-05perf/ioctl: Add check for the sample_period valueRavi Bangoria
commit 913a90bc5a3a06b1f04c337320e9aeee2328dd77 upstream. perf_event_open() limits the sample_period to 63 bits. See: 0819b2e30ccb ("perf: Limit perf_event_attr::sample_period to 63 bits") Make ioctl() consistent with it. Also on PowerPC, negative sample_period could cause a recursive PMIs leading to a hang (reported when running perf-fuzzer). Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Stephane Eranian <eranian@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vince Weaver <vincent.weaver@maine.edu> Cc: acme@kernel.org Cc: linuxppc-dev@lists.ozlabs.org Cc: maddy@linux.vnet.ibm.com Cc: mpe@ellerman.id.au Fixes: 0819b2e30ccb ("perf: Limit perf_event_attr::sample_period to 63 bits") Link: https://lkml.kernel.org/r/20190604042953.914-1-ravi.bangoria@linux.ibm.com Signed-off-by: Ingo Molnar <mingo@kernel.org> [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
2019-10-05perf/core: Fix perf_sample_regs_user() mm checkPeter Zijlstra
commit 085ebfe937d7a7a5df1729f35a12d6d655fea68c upstream. perf_sample_regs_user() uses 'current->mm' to test for the presence of userspace, but this is insufficient, consider use_mm(). A better test is: '!(current->flags & PF_KTHREAD)', exec() clears PF_KTHREAD after it sets the new ->mm but before it drops to userspace for the first time. Possibly obsoletes: bf05fc25f268 ("powerpc/perf: Fix oops when kthread execs user process") Reported-by: Ravi Bangoria <ravi.bangoria@linux.vnet.ibm.com> Reported-by: Young Xiao <92siuyang@gmail.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Will Deacon <will.deacon@arm.com> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Stephane Eranian <eranian@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Fixes: 4018994f3d87 ("perf: Add ability to attach user level registers dump to sample") Signed-off-by: Ingo Molnar <mingo@kernel.org> [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
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