linux/kernel, branch v3.4.95

nohz: Fix another inconsistency between CONFIG_NO_HZ=n and nohz=off

2014-06-26T19:10:29Z

commit 0e576acbc1d9600cf2d9b4a141a2554639959d50 upstream. If CONFIG_NO_HZ=n tick_nohz_get_sleep_length() returns NSEC_PER_SEC/HZ. If CONFIG_NO_HZ=y and the nohz functionality is disabled via the command line option "nohz=off" or not enabled due to missing hardware support, then tick_nohz_get_sleep_length() returns 0. That happens because ts->sleep_length is never set in that case. Set it to NSEC_PER_SEC/HZ when the NOHZ mode is inactive. Reported-by: Michal Hocko Reported-by: Borislav Petkov Signed-off-by: Thomas Gleixner Cc: Rui Xiang Signed-off-by: Greg Kroah-Hartman

auditsc: audit_krule mask accesses need bounds checking

2014-06-16T20:45:46Z

commit a3c54931199565930d6d84f4c3456f6440aefd41 upstream. Fixes an easy DoS and possible information disclosure. This does nothing about the broken state of x32 auditing. eparis: If the admin has enabled auditd and has specifically loaded audit rules. This bug has been around since before git. Wow... Signed-off-by: Andy Lutomirski Signed-off-by: Eric Paris Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

sched: Fix hotplug vs. set_cpus_allowed_ptr()

2014-06-11T19:04:11Z

commit 6acbfb96976fc3350e30d964acb1dbbdf876d55e upstream. Lai found that: WARNING: CPU: 1 PID: 13 at arch/x86/kernel/smp.c:124 native_smp_send_reschedule+0x2d/0x4b() ... migration_cpu_stop+0x1d/0x22 was caused by set_cpus_allowed_ptr() assuming that cpu_active_mask is always a sub-set of cpu_online_mask. This isn't true since 5fbd036b552f ("sched: Cleanup cpu_active madness"). So set active and online at the same time to avoid this particular problem. Fixes: 5fbd036b552f ("sched: Cleanup cpu_active madness") Signed-off-by: Lai Jiangshan Signed-off-by: Peter Zijlstra Cc: Andrew Morton Cc: Gautham R. Shenoy Cc: Linus Torvalds Cc: Michael wang Cc: Paul Gortmaker Cc: Rafael J. Wysocki Cc: Srivatsa S. Bhat Cc: Toshi Kani Link: http://lkml.kernel.org/r/53758B12.8060609@cn.fujitsu.com Signed-off-by: Ingo Molnar Signed-off-by: Greg Kroah-Hartman

perf: Fix race in removing an event

2014-06-11T19:04:11Z

commit 46ce0fe97a6be7532ce6126bb26ce89fed81528c upstream. When removing a (sibling) event we do: raw_spin_lock_irq(&ctx->lock); perf_group_detach(event); raw_spin_unlock_irq(&ctx->lock); perf_remove_from_context(event); raw_spin_lock_irq(&ctx->lock); ... raw_spin_unlock_irq(&ctx->lock); Now, assuming the event is a sibling, it will be 'unreachable' for things like ctx_sched_out() because that iterates the groups->siblings, and we just unhooked the sibling. So, if during we get ctx_sched_out(), it will miss the event and not call event_sched_out() on it, leaving it programmed on the PMU. The subsequent perf_remove_from_context() call will find the ctx is inactive and only call list_del_event() to remove the event from all other lists. Hereafter we can proceed to free the event; while still programmed! Close this hole by moving perf_group_detach() inside the same ctx->lock region(s) perf_remove_from_context() has. The condition on inherited events only in __perf_event_exit_task() is likely complete crap because non-inherited events are part of groups too and we're tearing down just the same. But leave that for another patch. Most-likely-Fixes: e03a9a55b4e ("perf: Change close() semantics for group events") Reported-by: Vince Weaver Tested-by: Vince Weaver Much-staring-at-traces-by: Vince Weaver Much-staring-at-traces-by: Thomas Gleixner Cc: Arnaldo Carvalho de Melo Cc: Linus Torvalds Signed-off-by: Peter Zijlstra Link: http://lkml.kernel.org/r/20140505093124.GN17778@laptop.programming.kicks-ass.net Signed-off-by: Ingo Molnar Signed-off-by: Greg Kroah-Hartman

perf: Limit perf_event_attr::sample_period to 63 bits

2014-06-11T19:04:11Z

commit 0819b2e30ccb93edf04876237b6205eef84ec8d2 upstream. Vince reported that using a large sample_period (one with bit 63 set) results in wreckage since while the sample_period is fundamentally unsigned (negative periods don't make sense) the way we implement things very much rely on signed logic. So limit sample_period to 63 bits to avoid tripping over this. Reported-by: Vince Weaver Signed-off-by: Peter Zijlstra Link: http://lkml.kernel.org/n/tip-p25fhunibl4y3qi0zuqmyf4b@git.kernel.org Signed-off-by: Thomas Gleixner Signed-off-by: Greg Kroah-Hartman

perf: Prevent false warning in perf_swevent_add

2014-06-11T19:04:10Z

commit 39af6b1678afa5880dda7e375cf3f9d395087f6d upstream. The perf cpu offline callback takes down all cpu context events and releases swhash->swevent_hlist. This could race with task context software event being just scheduled on this cpu via perf_swevent_add while cpu hotplug code already cleaned up event's data. The race happens in the gap between the cpu notifier code and the cpu being actually taken down. Note that only cpu ctx events are terminated in the perf cpu hotplug code. It's easily reproduced with: $ perf record -e faults perf bench sched pipe while putting one of the cpus offline: # echo 0 > /sys/devices/system/cpu/cpu1/online Console emits following warning: WARNING: CPU: 1 PID: 2845 at kernel/events/core.c:5672 perf_swevent_add+0x18d/0x1a0() Modules linked in: CPU: 1 PID: 2845 Comm: sched-pipe Tainted: G W 3.14.0+ #256 Hardware name: Intel Corporation Montevina platform/To be filled by O.E.M., BIOS AMVACRB1.86C.0066.B00.0805070703 05/07/2008 0000000000000009 ffff880077233ab8 ffffffff81665a23 0000000000200005 0000000000000000 ffff880077233af8 ffffffff8104732c 0000000000000046 ffff88007467c800 0000000000000002 ffff88007a9cf2a0 0000000000000001 Call Trace: [] dump_stack+0x4f/0x7c [] warn_slowpath_common+0x8c/0xc0 [] warn_slowpath_null+0x1a/0x20 [] perf_swevent_add+0x18d/0x1a0 [] event_sched_in.isra.75+0x9e/0x1f0 [] group_sched_in+0x6a/0x1f0 [] ? sched_clock_local+0x25/0xa0 [] ctx_sched_in+0x1f6/0x450 [] perf_event_sched_in+0x6b/0xa0 [] perf_event_context_sched_in+0x7b/0xc0 [] __perf_event_task_sched_in+0x43e/0x460 [] ? put_lock_stats.isra.18+0xe/0x30 [] finish_task_switch+0xb8/0x100 [] __schedule+0x30e/0xad0 [] ? pipe_read+0x3e2/0x560 [] ? preempt_schedule_irq+0x3e/0x70 [] ? preempt_schedule_irq+0x3e/0x70 [] preempt_schedule_irq+0x44/0x70 [] retint_kernel+0x20/0x30 [] ? lockdep_sys_exit+0x1a/0x90 [] lockdep_sys_exit_thunk+0x35/0x67 [] ? sysret_check+0x5/0x56 Fixing this by tracking the cpu hotplug state and displaying the WARN only if current cpu is initialized properly. Cc: Corey Ashford Cc: Frederic Weisbecker Cc: Ingo Molnar Cc: Paul Mackerras Cc: Arnaldo Carvalho de Melo Reported-by: Fengguang Wu Signed-off-by: Jiri Olsa Signed-off-by: Peter Zijlstra Link: http://lkml.kernel.org/r/1396861448-10097-1-git-send-email-jolsa@redhat.com Signed-off-by: Thomas Gleixner Signed-off-by: Greg Kroah-Hartman

sched: Use CPUPRI_NR_PRIORITIES instead of MAX_RT_PRIO in cpupri check

2014-06-11T19:04:10Z

commit 6227cb00cc120f9a43ce8313bb0475ddabcb7d01 upstream. The check at the beginning of cpupri_find() makes sure that the task_pri variable does not exceed the cp->pri_to_cpu array length. But that length is CPUPRI_NR_PRIORITIES not MAX_RT_PRIO, where it will miss the last two priorities in that array. As task_pri is computed from convert_prio() which should never be bigger than CPUPRI_NR_PRIORITIES, if the check should cause a panic if it is hit. Reported-by: Mike Galbraith Signed-off-by: Steven Rostedt Signed-off-by: Peter Zijlstra Link: http://lkml.kernel.org/r/1397015410.5212.13.camel@marge.simpson.net Signed-off-by: Ingo Molnar Signed-off-by: Greg Kroah-Hartman

futex: Make lookup_pi_state more robust

2014-06-07T23:02:16Z

commit 54a217887a7b658e2650c3feff22756ab80c7339 upstream. The current implementation of lookup_pi_state has ambigous handling of the TID value 0 in the user space futex. We can get into the kernel even if the TID value is 0, because either there is a stale waiters bit or the owner died bit is set or we are called from the requeue_pi path or from user space just for fun. The current code avoids an explicit sanity check for pid = 0 in case that kernel internal state (waiters) are found for the user space address. This can lead to state leakage and worse under some circumstances. Handle the cases explicit: Waiter | pi_state | pi->owner | uTID | uODIED | ? [1] NULL | --- | --- | 0 | 0/1 | Valid [2] NULL | --- | --- | >0 | 0/1 | Valid [3] Found | NULL | -- | Any | 0/1 | Invalid [4] Found | Found | NULL | 0 | 1 | Valid [5] Found | Found | NULL | >0 | 1 | Invalid [6] Found | Found | task | 0 | 1 | Valid [7] Found | Found | NULL | Any | 0 | Invalid [8] Found | Found | task | ==taskTID | 0/1 | Valid [9] Found | Found | task | 0 | 0 | Invalid [10] Found | Found | task | !=taskTID | 0/1 | Invalid [1] Indicates that the kernel can acquire the futex atomically. We came came here due to a stale FUTEX_WAITERS/FUTEX_OWNER_DIED bit. [2] Valid, if TID does not belong to a kernel thread. If no matching thread is found then it indicates that the owner TID has died. [3] Invalid. The waiter is queued on a non PI futex [4] Valid state after exit_robust_list(), which sets the user space value to FUTEX_WAITERS | FUTEX_OWNER_DIED. [5] The user space value got manipulated between exit_robust_list() and exit_pi_state_list() [6] Valid state after exit_pi_state_list() which sets the new owner in the pi_state but cannot access the user space value. [7] pi_state->owner can only be NULL when the OWNER_DIED bit is set. [8] Owner and user space value match [9] There is no transient state which sets the user space TID to 0 except exit_robust_list(), but this is indicated by the FUTEX_OWNER_DIED bit. See [4] [10] There is no transient state which leaves owner and user space TID out of sync. Signed-off-by: Thomas Gleixner Cc: Kees Cook Cc: Will Drewry Cc: Darren Hart Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

futex: Always cleanup owner tid in unlock_pi

2014-06-07T23:02:16Z

commit 13fbca4c6ecd96ec1a1cfa2e4f2ce191fe928a5e upstream. If the owner died bit is set at futex_unlock_pi, we currently do not cleanup the user space futex. So the owner TID of the current owner (the unlocker) persists. That's observable inconsistant state, especially when the ownership of the pi state got transferred. Clean it up unconditionally. Signed-off-by: Thomas Gleixner Cc: Kees Cook Cc: Will Drewry Cc: Darren Hart Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

futex: Validate atomic acquisition in futex_lock_pi_atomic()

2014-06-07T23:02:16Z

commit b3eaa9fc5cd0a4d74b18f6b8dc617aeaf1873270 upstream. We need to protect the atomic acquisition in the kernel against rogue user space which sets the user space futex to 0, so the kernel side acquisition succeeds while there is existing state in the kernel associated to the real owner. Verify whether the futex has waiters associated with kernel state. If it has, return -EINVAL. The state is corrupted already, so no point in cleaning it up. Subsequent calls will fail as well. Not our problem. [ tglx: Use futex_top_waiter() and explain why we do not need to try restoring the already corrupted user space state. ] Signed-off-by: Darren Hart Cc: Kees Cook Cc: Will Drewry Signed-off-by: Thomas Gleixner Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman