From 288874a97d33df16756a3874686562313e150f80 Mon Sep 17 00:00:00 2001 From: kib Date: Fri, 31 Oct 2008 10:38:30 +0000 Subject: The code in linux_proc_exit() contains a race when multiple linux based processes exits at the same time. The linux_emuldata structure is freed but p->p_emuldata is left as a dangling pointer to the just freed memory. The check for W_EXIT in the loop scanning the child processes isn't safe since the state of the child process can change right afterwards. Lock the process and check the W_EXIT before delivering signal. Submitted by: tegge Reviewed by: davidxu MFC after: 1 week --- sys/compat/linux/linux_emul.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'sys/compat') diff --git a/sys/compat/linux/linux_emul.c b/sys/compat/linux/linux_emul.c index 16e6033..1ca48a3 100644 --- a/sys/compat/linux/linux_emul.c +++ b/sys/compat/linux/linux_emul.c @@ -235,11 +235,11 @@ linux_proc_exit(void *arg __unused, struct proc *p) continue; em = em_find(q, EMUL_DOLOCK); KASSERT(em != NULL, ("linux_reparent: emuldata not found: %i\n", q->p_pid)); - if (em->pdeath_signal != 0) { - PROC_LOCK(q); + PROC_LOCK(q); + if ((q->p_flag & P_WEXIT) == 0 && em->pdeath_signal != 0) { psignal(q, em->pdeath_signal); - PROC_UNLOCK(q); } + PROC_UNLOCK(q); EMUL_UNLOCK(&emul_lock); } sx_xunlock(&proctree_lock); -- cgit v1.1