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authorCong Wang <xiyou.wangcong@gmail.com>2017-07-09 13:19:55 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2017-07-09 14:37:19 -0700
commitf991af3daabaecff34684fd51fac80319d1baad1 (patch)
tree7f71fafa6bf93eb11a214aa9758036482923ee0b /ipc
parent2b976203417cf033079e0be30cae5f41d88e385e (diff)
download96b-common-f991af3daabaecff34684fd51fac80319d1baad1.tar.gz
mqueue: fix a use-after-free in sys_mq_notify()
The retry logic for netlink_attachskb() inside sys_mq_notify() is nasty and vulnerable: 1) The sock refcnt is already released when retry is needed 2) The fd is controllable by user-space because we already release the file refcnt so we when retry but the fd has been just closed by user-space during this small window, we end up calling netlink_detachskb() on the error path which releases the sock again, later when the user-space closes this socket a use-after-free could be triggered. Setting 'sock' to NULL here should be sufficient to fix it. Reported-by: GeneBlue <geneblue.mail@gmail.com> Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Manfred Spraul <manfred@colorfullife.com> Cc: stable@kernel.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'ipc')
-rw-r--r--ipc/mqueue.c4
1 files changed, 3 insertions, 1 deletions
diff --git a/ipc/mqueue.c b/ipc/mqueue.c
index c9ff943f19ab..eb1391b52c6f 100644
--- a/ipc/mqueue.c
+++ b/ipc/mqueue.c
@@ -1270,8 +1270,10 @@ retry:
timeo = MAX_SCHEDULE_TIMEOUT;
ret = netlink_attachskb(sock, nc, &timeo, NULL);
- if (ret == 1)
+ if (ret == 1) {
+ sock = NULL;
goto retry;
+ }
if (ret) {
sock = NULL;
nc = NULL;