svn commit: r336205 - head/sys/kern
Alan Somers
asomers at FreeBSD.org
Wed Jul 11 19:38:43 UTC 2018
Author: asomers
Date: Wed Jul 11 19:38:42 2018
New Revision: 336205
URL: https://svnweb.freebsd.org/changeset/base/336205
Log:
Don't acquire evclass_lock with a spinlock held
When the "pc" audit class is enabled and auditd is running, witness will
panic during thread exit because au_event_class tries to lock an rwlock
while holding a spinlock acquired upstack by thread_exit.
To fix this, move AUDIT_SYSCALL_EXIT futher upstack, before the spinlock is
acquired. Of thread_exit's 16 callers, it's only necessary to call
AUDIT_SYSCALL_EXIT from two, exit1 (for exiting processes) and kern_thr_exit
(for exiting threads). The other callers are all kernel threads, which
needen't call AUDIT_SYSCALL_EXIT because since they can't make syscalls
there will be nothing to audit. And exit1 already does call
AUDIT_SYSCALL_EXIT, making the second call in thread_exit redundant for that
case.
PR: 228444
Reported by: aniketp
Reviewed by: aniketp, kib
MFC after: 2 weeks
Differential Revision: https://reviews.freebsd.org/D16210
Modified:
head/sys/kern/kern_thr.c
head/sys/kern/kern_thread.c
Modified: head/sys/kern/kern_thr.c
==============================================================================
--- head/sys/kern/kern_thr.c Wed Jul 11 19:23:11 2018 (r336204)
+++ head/sys/kern/kern_thr.c Wed Jul 11 19:38:42 2018 (r336205)
@@ -374,6 +374,11 @@ kern_thr_exit(struct thread *td)
KASSERT(p->p_numthreads > 1, ("too few threads"));
racct_sub(p, RACCT_NTHR, 1);
tdsigcleanup(td);
+
+#ifdef AUDIT
+ AUDIT_SYSCALL_EXIT(0, td);
+#endif
+
PROC_SLOCK(p);
thread_stopped(p);
thread_exit();
Modified: head/sys/kern/kern_thread.c
==============================================================================
--- head/sys/kern/kern_thread.c Wed Jul 11 19:23:11 2018 (r336204)
+++ head/sys/kern/kern_thread.c Wed Jul 11 19:38:42 2018 (r336205)
@@ -532,9 +532,6 @@ thread_exit(void)
SDT_PROBE0(proc, , , lwp__exit);
KASSERT(TAILQ_EMPTY(&td->td_sigqueue.sq_list), ("signal pending"));
-#ifdef AUDIT
- AUDIT_SYSCALL_EXIT(0, td);
-#endif
/*
* drop FPU & debug register state storage, or any other
* architecture specific resources that
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