Differential D49529

proc: Disallow re-enabling of process itimers during exit
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Authored by markj on Mar 27 2025, 10:32 AM.

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rG693664482649: proc: Disallow re-enabling of process itimers during exit
rGa6268f89d58c: proc: Disallow re-enabling of process itimers during exit

Summary

During process exit, it's possible for the exiting thread to send a
signal to its process, via killjobc(). This happens after the itimer is
drained. If itimers are stopped, i.e., P2_ITSTOPPED is set, then
itimer_proc_continue() will resume the callout after it has been
drained.

Fix the problem by simply clearing P2_ITSTOPPED as part of the drain.
Then, a signal received after that point will not re-enable the callout.

Reported by: syzkaller

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rG FreeBSD src repository

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Buildable 63170
Build 60054: arc lint + arc unit

Event Timeline

markj created this revision.Mar 27 2025, 10:32 AM

Herald added subscribers: olce, imp. · View Herald TranscriptMar 27 2025, 10:32 AM

markj requested review of this revision.Mar 27 2025, 10:32 AM

Harbormaster completed remote builds in B63148: Diff 152733.Mar 27 2025, 10:32 AM

I think this is fine.
But also I suggest to add the check for P_WEXIT/P_KILLED before re-arming the itimer callouts.

This revision is now accepted and ready to land.Mar 27 2025, 4:59 PM

Check for P_WEXIT in realitexpire_reset_callout() too.

This revision now requires review to proceed.Mar 28 2025, 8:54 AM

Harbormaster completed remote builds in B63170: Diff 152782.Mar 28 2025, 8:54 AM

kib accepted this revision.Mar 28 2025, 3:22 PM

This revision is now accepted and ready to land.Mar 28 2025, 3:22 PM

Closed by commit rGa6268f89d58c: proc: Disallow re-enabling of process itimers during exit (authored by markj). · Explain WhyMar 31 2025, 9:07 AM

This revision was automatically updated to reflect the committed changes.

markj added a commit: rGa6268f89d58c: proc: Disallow re-enabling of process itimers during exit.

markj added a commit: rG693664482649: proc: Disallow re-enabling of process itimers during exit.Apr 15 2025, 2:25 AM

Revision Contents
Changeset List

Path

Size

sys/

kern/

1 line

2 lines

Diff 152782

sys/kern/kern_exit.c

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sys/kern/kern_time.c

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