proc: Disallow re-enabling of process itimers during exit

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.
For good measure, also make sure that we don't reset the itimer callout
in an exiting process.

Reported by:	syzkaller
Reviewed by:	kib
MFC after:	2 weeks
Differential Revision:	https://reviews.freebsd.org/D49529

0 files changed, 0 insertions, 0 deletions