The patch titled
signalfd: fix interaction with posix-timers
has been added to the -mm tree. Its filename is
signalfd-fix-interaction-with-posix-timers.patch
*** Remember to use Documentation/SubmitChecklist when testing your code ***
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: signalfd: fix interaction with posix-timers
From: Oleg Nesterov <oleg@xxxxxxxxxx>
dequeue_signal:
if (__SI_TIMER) {
spin_unlock(&tsk->sighand->siglock);
do_schedule_next_timer(info);
spin_lock(&tsk->sighand->siglock);
}
Unless tsk == curent, this is absolutely unsafe: nothing prevents tsk from
exiting. If signalfd was passed to another process, do_schedule_next_timer()
is just wrong.
Add yet another "tsk == current" check into dequeue_signal().
This patch fixes an oopsable bug, but breaks the scheduling of posix timers
if the shared __SI_TIMER signal was fetched via signalfd attached to another
sub-thread. Mostly fixed by the next patch.
Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
Cc: Davide Libenzi <davidel@xxxxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Cc: Michael Kerrisk <mtk-manpages@xxxxxxx>
Cc: Roland McGrath <roland@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/signal.c | 4 ++--
1 files changed, 2 insertions(+), 2 deletions(-)
diff -puN kernel/signal.c~signalfd-fix-interaction-with-posix-timers kernel/signal.c
--- a/kernel/signal.c~signalfd-fix-interaction-with-posix-timers
+++ a/kernel/signal.c
@@ -378,7 +378,7 @@ int dequeue_signal(struct task_struct *t
/* We only dequeue private signals from ourselves, we don't let
* signalfd steal them
*/
- if (tsk == current)
+ if (likely(tsk == current))
signr = __dequeue_signal(&tsk->pending, mask, info);
if (!signr) {
signr = __dequeue_signal(&tsk->signal->shared_pending,
@@ -425,7 +425,7 @@ int dequeue_signal(struct task_struct *t
if (!(tsk->signal->flags & SIGNAL_GROUP_EXIT))
tsk->signal->flags |= SIGNAL_STOP_DEQUEUED;
}
- if ( signr &&
+ if (signr && likely(tsk == current) &&
((info->si_code & __SI_MASK) == __SI_TIMER) &&
info->si_sys_private){
/*
_
Patches currently in -mm which might be from oleg@xxxxxxxxxx are
origin.patch
posix-timers-fix-creation-race.patch
signalfd-fix-interaction-with-posix-timers.patch
signalfd-make-it-group-wide-fix-posix-timers-scheduling.patch
git-dvb.patch
clone-flag-clone_parent_tidptr-leaves-invalid-results-in-memory.patch
do_sys_poll-simplify-playing-with-on-stack-data.patch
do_sys_poll-simplify-playing-with-on-stack-data-fix.patch
do_poll-return-eintr-when-signalled.patch
pi-futex-set-pf_exiting-without-taking-pi_lock.patch
do_sigaction-remove-now-unneeded-recalc_sigpending.patch
handle-the-multi-threaded-inits-exit-properly.patch
wait_task_zombie-remove-unneeded-child-signal-check.patch
wait_task_zombie-fix-2-3-races-vs-forget_original_parent.patch
exit_notify-dont-take-tasklist-for-tif_sigpending-re-targeting.patch
zap_other_threads-dont-optimize-thread_group_empty-case.patch
cpu-hotplug-slab-cleanup-cpuup_callback.patch
cpu-hotplug-slab-fix-memory-leak-in-cpu-hotplug-error-path.patch
cpu-hotplug-cpu-deliver-cpu_up_canceled-only-to-notify_oked-callbacks-with-cpu_up_prepare.patch
cpu-hotplug-topology-remove-topology_dev_map.patch
cpu-hotplug-thermal_throttle-fix-cpu-hotplug-error-handling.patch
cpu-hotplug-msr-fix-cpu-hotplug-error-handling.patch
cpu-hotplug-cpuid-fix-cpu-hotplug-error-handling.patch
cpu-hotplug-mce-fix-cpu-hotplug-error-handling.patch
cpu-hotplug-intel_cacheinfo-fix-cpu-hotplug-error-handling.patch
cpu-hotplug-intel_cacheinfo-fix-cpu-hotplug-error-handling-fix-a-section-mismatch-warning.patch
make-access-to-tasks-nsproxy-lighter.patch
workqueue-debug-flushing-deadlocks-with-lockdep.patch
workqueue-debug-work-related-deadlocks-with-lockdep.patch
pid-namespaces-rework-forget_original_parent.patch
pid-namespaces-move-exit_task_namespaces.patch
pid-namespaces-introduce-ms_kernmount-flag.patch
pid-namespaces-prepare-proc_flust_task-to-flush-entries-from-multiple-proc-trees.patch
pid-namespaces-introduce-struct-upid.patch
pid-namespaces-add-support-for-pid-namespaces-hierarchy.patch
pid-namespaces-make-alloc_pid-free_pid-and-put_pid-work-with-struct-upid.patch
pid-namespaces-helpers-to-obtain-pid-numbers.patch
pid-namespaces-helpers-to-find-the-task-by-its-numerical-ids.patch
pid-namespaces-move-alloc_pid-lower-in-copy_process.patch
pid-namespaces-make-proc-have-multiple-superblocks-one-for-each-namespace.patch
pid-namespaces-miscelaneous-preparations-for-pid-namespaces.patch
pid-namespaces-allow-cloning-of-new-namespace.patch
pid-namespaces-make-proc_flush_task-actually-from-entries-from-multiple-namespaces.patch
pid-namespaces-initialize-the-namespaces-proc_mnt.patch
pid-namespaces-create-a-slab-cache-for-struct-pid_namespace.patch
pid-namespaces-allow-signalling-container-init.patch
pid-namespaces-destroy-pid-namespace-on-inits-death.patch
pid-namespaces-changes-to-show-virtual-ids-to-user.patch
pid-namespaces-remove-the-struct-pid-unneeded-fields.patch
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