user/sven/linux.git/kernel, branch v4.1.9

unshare: Unsharing a thread does not require unsharing a vm

2015-09-29T17:25:56Z

commit 12c641ab8270f787dfcce08b5f20ce8b65008096 upstream. In the logic in the initial commit of unshare made creating a new thread group for a process, contingent upon creating a new memory address space for that process. That is wrong. Two separate processes in different thread groups can share a memory address space and clone allows creation of such proceses. This is significant because it was observed that mm_users > 1 does not mean that a process is multi-threaded, as reading /proc/PID/maps temporarily increments mm_users, which allows other processes to (accidentally) interfere with unshare() calls. Correct the check in check_unshare_flags() to test for !thread_group_empty() for CLONE_THREAD, CLONE_SIGHAND, and CLONE_VM. For sighand->count > 1 for CLONE_SIGHAND and CLONE_VM. For !current_is_single_threaded instead of mm_users > 1 for CLONE_VM. By using the correct checks in unshare this removes the possibility of an accidental denial of service attack. Additionally using the correct checks in unshare ensures that only an explicit unshare(CLONE_VM) can possibly trigger the slow path of current_is_single_threaded(). As an explict unshare(CLONE_VM) is pointless it is not expected there are many applications that make that call. Fixes: b2e0d98705e60e45bbb3c0032c48824ad7ae0704 userns: Implement unshare of the user namespace Reported-by: Ricky Zhou Reported-by: Kees Cook Reviewed-by: Kees Cook Signed-off-by: "Eric W. Biederman" Signed-off-by: Greg Kroah-Hartman

fs: create and use seq_show_option for escaping

2015-09-21T17:05:45Z

commit a068acf2ee77693e0bf39d6e07139ba704f461c3 upstream. Many file systems that implement the show_options hook fail to correctly escape their output which could lead to unescaped characters (e.g. new lines) leaking into /proc/mounts and /proc/[pid]/mountinfo files. This could lead to confusion, spoofed entries (resulting in things like systemd issuing false d-bus "mount" notifications), and who knows what else. This looks like it would only be the root user stepping on themselves, but it's possible weird things could happen in containers or in other situations with delegated mount privileges. Here's an example using overlay with setuid fusermount trusting the contents of /proc/mounts (via the /etc/mtab symlink). Imagine the use of "sudo" is something more sneaky: $ BASE="ovl" $ MNT="$BASE/mnt" $ LOW="$BASE/lower" $ UP="$BASE/upper" $ WORK="$BASE/work/ 0 0 none /proc fuse.pwn user_id=1000" $ mkdir -p "$LOW" "$UP" "$WORK" $ sudo mount -t overlay -o "lowerdir=$LOW,upperdir=$UP,workdir=$WORK" none /mnt $ cat /proc/mounts none /root/ovl/mnt overlay rw,relatime,lowerdir=ovl/lower,upperdir=ovl/upper,workdir=ovl/work/ 0 0 none /proc fuse.pwn user_id=1000 0 0 $ fusermount -u /proc $ cat /proc/mounts cat: /proc/mounts: No such file or directory This fixes the problem by adding new seq_show_option and seq_show_option_n helpers, and updating the vulnerable show_option handlers to use them as needed. Some, like SELinux, need to be open coded due to unusual existing escape mechanisms. [akpm@linux-foundation.org: add lost chunk, per Kees] [keescook@chromium.org: seq_show_option should be using const parameters] Signed-off-by: Kees Cook Acked-by: Serge Hallyn Acked-by: Jan Kara Acked-by: Paul Moore Cc: J. R. Okajima Signed-off-by: Kees Cook Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

sched: Fix cpu_active_mask/cpu_online_mask race

2015-09-21T17:05:29Z

commit dd9d3843755da95f63dd3a376f62b3e45c011210 upstream. There is a race condition in SMP bootup code, which may result in WARNING: CPU: 0 PID: 1 at kernel/workqueue.c:4418 workqueue_cpu_up_callback() or kernel BUG at kernel/smpboot.c:135! It can be triggered with a bit of luck in Linux guests running on busy hosts. CPU0 CPUn ==== ==== _cpu_up() __cpu_up() start_secondary() set_cpu_online() cpumask_set_cpu(cpu, to_cpumask(cpu_online_bits)); cpu_notify(CPU_ONLINE) cpumask_set_cpu(cpu, to_cpumask(cpu_active_bits)); During the various CPU_ONLINE callbacks CPUn is online but not active. Several things can go wrong at that point, depending on the scheduling of tasks on CPU0. Variant 1: cpu_notify(CPU_ONLINE) workqueue_cpu_up_callback() rebind_workers() set_cpus_allowed_ptr() This call fails because it requires an active CPU; rebind_workers() ends with a warning: WARNING: CPU: 0 PID: 1 at kernel/workqueue.c:4418 workqueue_cpu_up_callback() Variant 2: cpu_notify(CPU_ONLINE) smpboot_thread_call() smpboot_unpark_threads() .. __kthread_unpark() __kthread_bind() wake_up_state() .. select_task_rq() select_fallback_rq() The ->wake_cpu of the unparked thread is not allowed, making a call to select_fallback_rq() necessary. Then, select_fallback_rq() cannot find an allowed, active CPU and promptly resets the allowed CPUs, so that the task in question ends up on CPU0. When those unparked tasks are eventually executed, they run immediately into a BUG: kernel BUG at kernel/smpboot.c:135! Just changing the order in which the online/active bits are set (and adding some memory barriers), would solve the two issues above. However, it would change the order of operations back to the one before commit 6acbfb96976f ("sched: Fix hotplug vs. set_cpus_allowed_ptr()"), thus, reintroducing that particular problem. Going further back into history, we have at least the following commits touching this topic: - commit 2baab4e90495 ("sched: Fix select_fallback_rq() vs cpu_active/cpu_online") - commit 5fbd036b552f ("sched: Cleanup cpu_active madness") Together, these give us the following non-working solutions: - secondary CPU sets active before online, because active is assumed to be a subset of online; - secondary CPU sets online before active, because the primary CPU assumes that an online CPU is also active; - secondary CPU sets online and waits for primary CPU to set active, because it might deadlock. Commit 875ebe940d77 ("powerpc/smp: Wait until secondaries are active & online") introduces an arch-specific solution to this arch-independent problem. Now, go for a more general solution without explicit waiting and simply set active twice: once on the secondary CPU after online was set and once on the primary CPU after online was seen. set_cpus_allowed_ptr()") Signed-off-by: Jan H. Schönherr Acked-by: Peter Zijlstra Cc: Anton Blanchard Cc: Borislav Petkov Cc: Joerg Roedel Cc: Linus Torvalds Cc: Matt Wilson Cc: Michael Ellerman Cc: Peter Zijlstra Cc: Thomas Gleixner Fixes: 6acbfb96976f ("sched: Fix hotplug vs. set_cpus_allowed_ptr()") Link: http://lkml.kernel.org/r/1439408156-18840-1-git-send-email-jschoenh@amazon.de Signed-off-by: Ingo Molnar Signed-off-by: Greg Kroah-Hartman

genirq: Introduce irq_chip_set_type_parent() helper

2015-09-13T16:07:51Z

commit b7560de198222994374c1340a389f12d5efb244a upstream. This helper is required for irq chips which do not implement a irq_set_type callback and need to call down the irq domain hierarchy for the actual trigger type change. This helper is required to fix further wreckage caused by the conversion of TI OMAP to hierarchical irq domains and therefor tagged for stable. [ tglx: Massaged changelog ] Signed-off-by: Grygorii Strashko Cc: Sudeep Holla Cc: Cc: Cc: Cc: Cc: Cc: Cc: Cc: stable@vger.kernel.org # 4.1 Link: http://lkml.kernel.org/r/1439554830-19502-3-git-send-email-grygorii.strashko@ti.com Signed-off-by: Thomas Gleixner Signed-off-by: Greg Kroah-Hartman

genirq: Don't return ENOSYS in irq_chip_retrigger_hierarchy

2015-09-13T16:07:51Z

commit 6d4affea7d5aa5ca5ff4c3e5fbf3ee16801cc527 upstream. irq_chip_retrigger_hierarchy() returns -ENOSYS if it was not able to find at least one .irq_retrigger() callback implemented in the IRQ domain hierarchy. That's wrong, because check_irq_resend() expects a 0 return value from the callback in case that the hardware assisted resend was not possible. If the return value is non zero the core code assumes hardware resend success and the software resend is not invoked. This results in lost interrupts on platforms where none of the parent irq chips in the hierarchy implements the retrigger callback. This is observable on TI OMAP, where the hierarchy is: ARM GIC <- OMAP wakeupgen <- TI Crossbar Return 0 instead so the software resend mechanism gets invoked. [ tglx: Massaged changelog ] Fixes: 85f08c17de26 ('genirq: Introduce helper functions...') Signed-off-by: Grygorii Strashko Reviewed-by: Marc Zyngier Reviewed-by: Jiang Liu Cc: Sudeep Holla Cc: Cc: Cc: Cc: Cc: Cc: Link: http://lkml.kernel.org/r/1439554830-19502-2-git-send-email-grygorii.strashko@ti.com Signed-off-by: Thomas Gleixner Signed-off-by: Greg Kroah-Hartman

cpuset: use trialcs->mems_allowed as a temp variable

2015-09-13T16:07:46Z

commit 24ee3cf89bef04e8bc23788aca4e029a3f0f06d9 upstream. The comment says it's using trialcs->mems_allowed as a temp variable but it didn't match the code. Change the code to match the comment. This fixes an issue when writing in cpuset.mems when a sub-directory exists: we need to write several times for the information to persist: | root@alban:/sys/fs/cgroup/cpuset# mkdir footest9 | root@alban:/sys/fs/cgroup/cpuset# cd footest9 | root@alban:/sys/fs/cgroup/cpuset/footest9# mkdir aa | root@alban:/sys/fs/cgroup/cpuset/footest9# cat cpuset.mems | | root@alban:/sys/fs/cgroup/cpuset/footest9# echo 0 > cpuset.mems | root@alban:/sys/fs/cgroup/cpuset/footest9# cat cpuset.mems | | root@alban:/sys/fs/cgroup/cpuset/footest9# echo 0 > cpuset.mems | root@alban:/sys/fs/cgroup/cpuset/footest9# cat cpuset.mems | 0 | root@alban:/sys/fs/cgroup/cpuset/footest9# cat aa/cpuset.mems | | root@alban:/sys/fs/cgroup/cpuset/footest9# echo 0 > aa/cpuset.mems | root@alban:/sys/fs/cgroup/cpuset/footest9# cat aa/cpuset.mems | 0 | root@alban:/sys/fs/cgroup/cpuset/footest9# This should help to fix the following issue in Docker: https://github.com/opencontainers/runc/issues/133 In some conditions, a Docker container needs to be started twice in order to work. Signed-off-by: Alban Crequy Tested-by: Iago López Galeiras Acked-by: Li Zefan Signed-off-by: Tejun Heo Signed-off-by: Greg Kroah-Hartman

perf: Fix PERF_EVENT_IOC_PERIOD migration race

2015-09-13T16:07:39Z

commit c7999c6f3fed9e383d3131474588f282ae6d56b9 upstream. I ran the perf fuzzer, which triggered some WARN()s which are due to trying to stop/restart an event on the wrong CPU. Use the normal IPI pattern to ensure we run the code on the correct CPU. Signed-off-by: Peter Zijlstra (Intel) Cc: Vince Weaver Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Fixes: bad7192b842c ("perf: Fix PERF_EVENT_IOC_PERIOD to force-reset the period") Signed-off-by: Ingo Molnar Signed-off-by: Greg Kroah-Hartman

perf: Fix double-free of the AUX buffer

2015-09-13T16:07:39Z

commit ee9397a6fb9bc4e52677f5e33eed4abee0f515e6 upstream. If rb->aux_refcount is decremented to zero before rb->refcount, __rb_free_aux() may be called twice resulting in a double free of rb->aux_pages. Fix this by adding a check to __rb_free_aux(). Signed-off-by: Ben Hutchings Signed-off-by: Peter Zijlstra (Intel) Cc: Alexander Shishkin Cc: Arnaldo Carvalho de Melo Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Fixes: 57ffc5ca679f ("perf: Fix AUX buffer refcounting") Link: http://lkml.kernel.org/r/1437953468.12842.17.camel@decadent.org.uk Signed-off-by: Ingo Molnar Signed-off-by: Greg Kroah-Hartman

perf: Fix running time accounting

2015-09-13T16:07:39Z

commit 00a2916f7f82c348a2a94dbb572874173bc308a3 upstream. A recent fix to the shadow timestamp inadvertly broke the running time accounting. We must not update the running timestamp if we fail to schedule the event, the event will not have ran. This can (and did) result in negative total runtime because the stopped timestamp was before the running timestamp (we 'started' but never stopped the event -- because it never really started we didn't have to stop it either). Reported-and-Tested-by: Vince Weaver Fixes: 72f669c0086f ("perf: Update shadow timestamp before add event") Signed-off-by: Peter Zijlstra (Intel) Cc: Shaohua Li Signed-off-by: Thomas Gleixner Signed-off-by: Greg Kroah-Hartman

perf: Fix fasync handling on inherited events

2015-09-13T16:07:39Z

commit fed66e2cdd4f127a43fd11b8d92a99bdd429528c upstream. Vince reported that the fasync signal stuff doesn't work proper for inherited events. So fix that. Installing fasync allocates memory and sets filp->f_flags |= FASYNC, which upon the demise of the file descriptor ensures the allocation is freed and state is updated. Now for perf, we can have the events stick around for a while after the original FD is dead because of references from child events. So we cannot copy the fasync pointer around. We can however consistently use the parent's fasync, as that will be updated. Reported-and-Tested-by: Vince Weaver Signed-off-by: Peter Zijlstra (Intel) Cc: Arnaldo Carvalho deMelo Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: eranian@google.com Link: http://lkml.kernel.org/r/1434011521.1495.71.camel@twins Signed-off-by: Ingo Molnar Signed-off-by: Greg Kroah-Hartman