user/sven/linux.git/kernel, branch v4.10.16

bpf: don't let ldimm64 leak map addresses on unprivileged

2017-05-14T12:08:29Z

[ Upstream commit 0d0e57697f162da4aa218b5feafe614fb666db07 ] The patch fixes two things at once: 1) It checks the env->allow_ptr_leaks and only prints the map address to the log if we have the privileges to do so, otherwise it just dumps 0 as we would when kptr_restrict is enabled on %pK. Given the latter is off by default and not every distro sets it, I don't want to rely on this, hence the 0 by default for unprivileged. 2) Printing of ldimm64 in the verifier log is currently broken in that we don't print the full immediate, but only the 32 bit part of the first insn part for ldimm64. Thus, fix this up as well; it's okay to access, since we verified all ldimm64 earlier already (including just constants) through replace_map_fd_with_map_ptr(). Fixes: 1be7f75d1668 ("bpf: enable non-root eBPF programs") Fixes: cbd357008604 ("bpf: verifier (add ability to receive verification log)") Reported-by: Jann Horn Signed-off-by: Daniel Borkmann Acked-by: Alexei Starovoitov Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman

bpf: enhance verifier to understand stack pointer arithmetic

2017-05-14T12:08:28Z

[ Upstream commit 332270fdc8b6fba07d059a9ad44df9e1a2ad4529 ] llvm 4.0 and above generates the code like below: .... 440: (b7) r1 = 15 441: (05) goto pc+73 515: (79) r6 = *(u64 *)(r10 -152) 516: (bf) r7 = r10 517: (07) r7 += -112 518: (bf) r2 = r7 519: (0f) r2 += r1 520: (71) r1 = *(u8 *)(r8 +0) 521: (73) *(u8 *)(r2 +45) = r1 .... and the verifier complains "R2 invalid mem access 'inv'" for insn #521. This is because verifier marks register r2 as unknown value after #519 where r2 is a stack pointer and r1 holds a constant value. Teach verifier to recognize "stack_ptr + imm" and "stack_ptr + reg with const val" as valid stack_ptr with new offset. Signed-off-by: Yonghong Song Acked-by: Martin KaFai Lau Acked-by: Daniel Borkmann Signed-off-by: Alexei Starovoitov Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman

cpu/hotplug: Serialize callback invocations proper

2017-05-03T15:37:43Z

commit dc434e056fe1dada20df7ba07f32739d3a701adf upstream. The setup/remove_state/instance() functions in the hotplug core code are serialized against concurrent CPU hotplug, but unfortunately not serialized against themself. As a consequence a concurrent invocation of these function results in corruption of the callback machinery because two instances try to invoke callbacks on remote cpus at the same time. This results in missing callback invocations and initiator threads waiting forever on the completion. The obvious solution to replace get_cpu_online() with cpu_hotplug_begin() is not possible because at least one callsite calls into these functions from a get_online_cpu() locked region. Extend the protection scope of the cpuhp_state_mutex from solely protecting the state arrays to cover the callback invocation machinery as well. Fixes: 5b7aa87e0482 ("cpu/hotplug: Implement setup/removal interface") Reported-and-tested-by: Bart Van Assche Signed-off-by: Sebastian Andrzej Siewior Cc: hpa@zytor.com Cc: mingo@kernel.org Cc: akpm@linux-foundation.org Cc: torvalds@linux-foundation.org Link: http://lkml.kernel.org/r/20170314150645.g4tdyoszlcbajmna@linutronix.de Signed-off-by: Thomas Gleixner Signed-off-by: Greg Kroah-Hartman

bpf: improve verifier packet range checks

2017-05-03T15:37:38Z

[ Upstream commit b1977682a3858b5584ffea7cfb7bd863f68db18d ] llvm can optimize the 'if (ptr > data_end)' checks to be in the order slightly different than the original C code which will confuse verifier. Like: if (ptr + 16 > data_end) return TC_ACT_SHOT; // may be followed by if (ptr + 14 > data_end) return TC_ACT_SHOT; while llvm can see that 'ptr' is valid for all 16 bytes, the verifier could not. Fix verifier logic to account for such case and add a test. Reported-by: Huapeng Zhou Fixes: 969bf05eb3ce ("bpf: direct packet access") Signed-off-by: Alexei Starovoitov Acked-by: Daniel Borkmann Acked-by: Martin KaFai Lau Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman

ring-buffer: Have ring_buffer_iter_empty() return true when empty

2017-04-27T07:12:57Z

commit 78f7a45dac2a2d2002f98a3a95f7979867868d73 upstream. I noticed that reading the snapshot file when it is empty no longer gives a status. It suppose to show the status of the snapshot buffer as well as how to allocate and use it. For example: ># cat snapshot # tracer: nop # # # * Snapshot is allocated * # # Snapshot commands: # echo 0 > snapshot : Clears and frees snapshot buffer # echo 1 > snapshot : Allocates snapshot buffer, if not already allocated. # Takes a snapshot of the main buffer. # echo 2 > snapshot : Clears snapshot buffer (but does not allocate or free) # (Doesn't have to be '2' works with any number that # is not a '0' or '1') But instead it just showed an empty buffer: ># cat snapshot # tracer: nop # # entries-in-buffer/entries-written: 0/0 #P:4 # # _-----=> irqs-off # / _----=> need-resched # | / _---=> hardirq/softirq # || / _--=> preempt-depth # ||| / delay # TASK-PID CPU# |||| TIMESTAMP FUNCTION # | | | |||| | | What happened was that it was using the ring_buffer_iter_empty() function to see if it was empty, and if it was, it showed the status. But that function was returning false when it was empty. The reason was that the iter header page was on the reader page, and the reader page was empty, but so was the buffer itself. The check only tested to see if the iter was on the commit page, but the commit page was no longer pointing to the reader page, but as all pages were empty, the buffer is also. Fixes: 651e22f2701b ("ring-buffer: Always reset iterator to reader page") Signed-off-by: Steven Rostedt (VMware) Signed-off-by: Greg Kroah-Hartman

tracing: Allocate the snapshot buffer before enabling probe

2017-04-27T07:12:57Z

commit df62db5be2e5f070ecd1a5ece5945b590ee112e0 upstream. Currently the snapshot trigger enables the probe and then allocates the snapshot. If the probe triggers before the allocation, it could cause the snapshot to fail and turn tracing off. It's best to allocate the snapshot buffer first, and then enable the trigger. If something goes wrong in the enabling of the trigger, the snapshot buffer is still allocated, but it can also be freed by the user by writting zero into the snapshot buffer file. Also add a check of the return status of alloc_snapshot(). Fixes: 77fd5c15e3 ("tracing: Add snapshot trigger to function probes") Signed-off-by: Steven Rostedt (VMware) Signed-off-by: Greg Kroah-Hartman

ftrace: Fix function pid filter on instances

2017-04-21T07:32:41Z

commit d879d0b8c183aabeb9a65eba91f3f9e3c7e7b905 upstream. When function tracer has a pid filter, it adds a probe to sched_switch to track if current task can be ignored. The probe checks the ftrace_ignore_pid from current tr to filter tasks. But it misses to delete the probe when removing an instance so that it can cause a crash due to the invalid tr pointer (use-after-free). This is easily reproducible with the following: # cd /sys/kernel/debug/tracing # mkdir instances/buggy # echo $$ > instances/buggy/set_ftrace_pid # rmdir instances/buggy ============================================================================ BUG: KASAN: use-after-free in ftrace_filter_pid_sched_switch_probe+0x3d/0x90 Read of size 8 by task kworker/0:1/17 CPU: 0 PID: 17 Comm: kworker/0:1 Tainted: G B 4.11.0-rc3 #198 Call Trace: dump_stack+0x68/0x9f kasan_object_err+0x21/0x70 kasan_report.part.1+0x22b/0x500 ? ftrace_filter_pid_sched_switch_probe+0x3d/0x90 kasan_report+0x25/0x30 __asan_load8+0x5e/0x70 ftrace_filter_pid_sched_switch_probe+0x3d/0x90 ? fpid_start+0x130/0x130 __schedule+0x571/0xce0 ... To fix it, use ftrace_clear_pids() to unregister the probe. As instance_rmdir() already updated ftrace codes, it can just free the filter safely. Link: http://lkml.kernel.org/r/20170417024430.21194-2-namhyung@kernel.org Fixes: 0c8916c34203 ("tracing: Add rmdir to remove multibuffer instances") Cc: Ingo Molnar Reviewed-by: Masami Hiramatsu Signed-off-by: Namhyung Kim Signed-off-by: Steven Rostedt (VMware) Signed-off-by: Greg Kroah-Hartman

ftrace: Fix removing of second function probe

2017-04-21T07:32:40Z

commit 82cc4fc2e70ec5baeff8f776f2773abc8b2cc0ae upstream. When two function probes are added to set_ftrace_filter, and then one of them is removed, the update to the function locations is not performed, and the record keeping of the function states are corrupted, and causes an ftrace_bug() to occur. This is easily reproducable by adding two probes, removing one, and then adding it back again. # cd /sys/kernel/debug/tracing # echo schedule:traceoff > set_ftrace_filter # echo do_IRQ:traceoff > set_ftrace_filter # echo \!do_IRQ:traceoff > /debug/tracing/set_ftrace_filter # echo do_IRQ:traceoff > set_ftrace_filter Causes: ------------[ cut here ]------------ WARNING: CPU: 2 PID: 1098 at kernel/trace/ftrace.c:2369 ftrace_get_addr_curr+0x143/0x220 Modules linked in: [...] CPU: 2 PID: 1098 Comm: bash Not tainted 4.10.0-test+ #405 Hardware name: Hewlett-Packard HP Compaq Pro 6300 SFF/339A, BIOS K01 v02.05 05/07/2012 Call Trace: dump_stack+0x68/0x9f __warn+0x111/0x130 ? trace_irq_work_interrupt+0xa0/0xa0 warn_slowpath_null+0x1d/0x20 ftrace_get_addr_curr+0x143/0x220 ? __fentry__+0x10/0x10 ftrace_replace_code+0xe3/0x4f0 ? ftrace_int3_handler+0x90/0x90 ? printk+0x99/0xb5 ? 0xffffffff81000000 ftrace_modify_all_code+0x97/0x110 arch_ftrace_update_code+0x10/0x20 ftrace_run_update_code+0x1c/0x60 ftrace_run_modify_code.isra.48.constprop.62+0x8e/0xd0 register_ftrace_function_probe+0x4b6/0x590 ? ftrace_startup+0x310/0x310 ? debug_lockdep_rcu_enabled.part.4+0x1a/0x30 ? update_stack_state+0x88/0x110 ? ftrace_regex_write.isra.43.part.44+0x1d3/0x320 ? preempt_count_sub+0x18/0xd0 ? mutex_lock_nested+0x104/0x800 ? ftrace_regex_write.isra.43.part.44+0x1d3/0x320 ? __unwind_start+0x1c0/0x1c0 ? _mutex_lock_nest_lock+0x800/0x800 ftrace_trace_probe_callback.isra.3+0xc0/0x130 ? func_set_flag+0xe0/0xe0 ? __lock_acquire+0x642/0x1790 ? __might_fault+0x1e/0x20 ? trace_get_user+0x398/0x470 ? strcmp+0x35/0x60 ftrace_trace_onoff_callback+0x48/0x70 ftrace_regex_write.isra.43.part.44+0x251/0x320 ? match_records+0x420/0x420 ftrace_filter_write+0x2b/0x30 __vfs_write+0xd7/0x330 ? do_loop_readv_writev+0x120/0x120 ? locks_remove_posix+0x90/0x2f0 ? do_lock_file_wait+0x160/0x160 ? __lock_is_held+0x93/0x100 ? rcu_read_lock_sched_held+0x5c/0xb0 ? preempt_count_sub+0x18/0xd0 ? __sb_start_write+0x10a/0x230 ? vfs_write+0x222/0x240 vfs_write+0xef/0x240 SyS_write+0xab/0x130 ? SyS_read+0x130/0x130 ? trace_hardirqs_on_caller+0x182/0x280 ? trace_hardirqs_on_thunk+0x1a/0x1c entry_SYSCALL_64_fastpath+0x18/0xad RIP: 0033:0x7fe61c157c30 RSP: 002b:00007ffe87890258 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: ffffffff8114a410 RCX: 00007fe61c157c30 RDX: 0000000000000010 RSI: 000055814798f5e0 RDI: 0000000000000001 RBP: ffff8800c9027f98 R08: 00007fe61c422740 R09: 00007fe61ca53700 R10: 0000000000000073 R11: 0000000000000246 R12: 0000558147a36400 R13: 00007ffe8788f160 R14: 0000000000000024 R15: 00007ffe8788f15c ? trace_hardirqs_off_caller+0xc0/0x110 ---[ end trace 99fa09b3d9869c2c ]--- Bad trampoline accounting at: ffffffff81cc3b00 (do_IRQ+0x0/0x150) Fixes: 59df055f1991 ("ftrace: trace different functions with a different tracer") Signed-off-by: Steven Rostedt (VMware) Signed-off-by: Greg Kroah-Hartman

audit: make sure we don't let the retry queue grow without bounds

2017-04-21T07:32:36Z

commit 264d509637d95f9404e52ced5003ad352e0f6a26 upstream. The retry queue is intended to provide a temporary buffer in the case of transient errors when communicating with auditd, it is not meant as a long life queue, that functionality is provided by the hold queue. This patch fixes a problem identified by Seth where the retry queue could grow uncontrollably if an auditd instance did not connect to the kernel to drain the queues. This commit fixes this by doing the following: * Make sure we always call auditd_reset() if we decide the connection with audit is really dead. There were some cases in kauditd_hold_skb() where we did not reset the connection, this patch relocates the reset calls to kauditd_thread() so all the error conditions are caught and the connection reset. As a side effect, this means we could move auditd_reset() and get rid of the forward definition at the top of kernel/audit.c. * We never checked the status of the auditd connection when processing the main audit queue which meant that the retry queue could grow unchecked. This patch adds a call to auditd_reset() after the main queue has been processed if auditd is not connected, the auditd_reset() call will make sure the retry and hold queues are correctly managed/flushed so that the retry queue remains reasonable. Reported-by: Seth Forshee Signed-off-by: Paul Moore Signed-off-by: Greg Kroah-Hartman

cgroup, kthread: close race window where new kthreads can be migrated to non-root cgroups

2017-04-21T07:32:36Z

commit 77f88796cee819b9c4562b0b6b44691b3b7755b1 upstream. Creation of a kthread goes through a couple interlocked stages between the kthread itself and its creator. Once the new kthread starts running, it initializes itself and wakes up the creator. The creator then can further configure the kthread and then let it start doing its job by waking it up. In this configuration-by-creator stage, the creator is the only one that can wake it up but the kthread is visible to userland. When altering the kthread's attributes from userland is allowed, this is fine; however, for cases where CPU affinity is critical, kthread_bind() is used to first disable affinity changes from userland and then set the affinity. This also prevents the kthread from being migrated into non-root cgroups as that can affect the CPU affinity and many other things. Unfortunately, the cgroup side of protection is racy. While the PF_NO_SETAFFINITY flag prevents further migrations, userland can win the race before the creator sets the flag with kthread_bind() and put the kthread in a non-root cgroup, which can lead to all sorts of problems including incorrect CPU affinity and starvation. This bug got triggered by userland which periodically tries to migrate all processes in the root cpuset cgroup to a non-root one. Per-cpu workqueue workers got caught while being created and ended up with incorrected CPU affinity breaking concurrency management and sometimes stalling workqueue execution. This patch adds task->no_cgroup_migration which disallows the task to be migrated by userland. kthreadd starts with the flag set making every child kthread start in the root cgroup with migration disallowed. The flag is cleared after the kthread finishes initialization by which time PF_NO_SETAFFINITY is set if the kthread should stay in the root cgroup. It'd be better to wait for the initialization instead of failing but I couldn't think of a way of implementing that without adding either a new PF flag, or sleeping and retrying from waiting side. Even if userland depends on changing cgroup membership of a kthread, it either has to be synchronized with kthread_create() or periodically repeat, so it's unlikely that this would break anything. v2: Switch to a simpler implementation using a new task_struct bit field suggested by Oleg. Signed-off-by: Tejun Heo Suggested-by: Oleg Nesterov Cc: Linus Torvalds Cc: Andrew Morton Cc: Peter Zijlstra (Intel) Cc: Thomas Gleixner Reported-and-debugged-by: Chris Mason Signed-off-by: Tejun Heo Signed-off-by: Greg Kroah-Hartman