K 10
svn:author
V 5
markj
K 8
svn:date
V 27
2021-08-23T00:44:32.697046Z
K 7
svn:log
V 944
sigtimedwait: Use a unique wait channel for sleeping

When a sigtimedwait(2) caller goes to sleep, it uses a wait channel of
p->p_sigacts with the proc lock as the interlock.  However, p_sigacts
can be shared between processes if a child is created with
rfork(RFSIGSHARE | RFPROC).  Thus we can end up with two threads
sleeping on the same wait channel using different locks, which is not
permitted.

Fix the problem simply by using a process-unique wait channel, following
the example of sigsuspend.  The actual wait channel value is irrelevant
here, sleeping threads are awoken using sleepq_abort().

Reported by:	syzbot+8c417afabadb50bb8827@syzkaller.appspotmail.com
Reported by:	syzbot+1d89fc2a9ef92ef64fa8@syzkaller.appspotmail.com
Reviewed by:	kib
Sponsored by:	The FreeBSD Foundation

(cherry picked from commit c4feb1ab0ae0c0e779af372e4c5f3b9e0d3e1388)

Git Hash:   75a60b2658254c974767a5407b9efbadd76ef017
Git Author: markj@FreeBSD.org
END