From 288874a97d33df16756a3874686562313e150f80 Mon Sep 17 00:00:00 2001
From: kib <kib@FreeBSD.org>
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/linux/linux_emul.c')
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);
--
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