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| author | Peter Zijlstra <peterz@infradead.org> | 2023-02-03 17:31:11 +0300 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2023-02-13 18:36:14 +0300 |
| commit | eedeb787ebb53de5c5dcf7b7b39d01bf1b0f037d (patch) | |
| tree | 62e298bf3aa2d36e0c7bab7d5d127b7ee6c5ab95 /kernel | |
| parent | ceaa837f96adb69c0df0397937cd74991d5d821a (diff) | |
| download | linux-eedeb787ebb53de5c5dcf7b7b39d01bf1b0f037d.tar.xz | |
freezer,umh: Fix call_usermode_helper_exec() vs SIGKILL
Tetsuo-San noted that commit f5d39b020809 ("freezer,sched: Rewrite
core freezer logic") broke call_usermodehelper_exec() for the KILLABLE
case.
Specifically it was missed that the second, unconditional,
wait_for_completion() was not optional and ensures the on-stack
completion is unused before going out-of-scope.
Fixes: f5d39b020809 ("freezer,sched: Rewrite core freezer logic")
Reported-by: syzbot+6cd18e123583550cf469@syzkaller.appspotmail.com
Reported-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Debugged-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/Y90ar35uKQoUrLEK@hirez.programming.kicks-ass.net
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/umh.c | 20 |
1 files changed, 13 insertions, 7 deletions
diff --git a/kernel/umh.c b/kernel/umh.c index 850631518665..fbf872c624cb 100644 --- a/kernel/umh.c +++ b/kernel/umh.c @@ -438,21 +438,27 @@ int call_usermodehelper_exec(struct subprocess_info *sub_info, int wait) if (wait == UMH_NO_WAIT) /* task has freed sub_info */ goto unlock; - if (wait & UMH_KILLABLE) - state |= TASK_KILLABLE; - if (wait & UMH_FREEZABLE) state |= TASK_FREEZABLE; - retval = wait_for_completion_state(&done, state); - if (!retval) - goto wait_done; - if (wait & UMH_KILLABLE) { + retval = wait_for_completion_state(&done, state | TASK_KILLABLE); + if (!retval) + goto wait_done; + /* umh_complete() will see NULL and free sub_info */ if (xchg(&sub_info->complete, NULL)) goto unlock; + + /* + * fallthrough; in case of -ERESTARTSYS now do uninterruptible + * wait_for_completion_state(). Since umh_complete() shall call + * complete() in a moment if xchg() above returned NULL, this + * uninterruptible wait_for_completion_state() will not block + * SIGKILL'ed processes for long. + */ } + wait_for_completion_state(&done, state); wait_done: retval = sub_info->retval; |