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| author | Cong Wang <xiyou.wangcong@gmail.com> | 2017-07-09 13:19:55 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2017-07-09 14:37:19 -0700 |
| commit | f991af3daabaecff34684fd51fac80319d1baad1 (patch) | |
| tree | 7f71fafa6bf93eb11a214aa9758036482923ee0b /ipc | |
| parent | 2b976203417cf033079e0be30cae5f41d88e385e (diff) | |
| download | lwn-f991af3daabaecff34684fd51fac80319d1baad1.tar.gz lwn-f991af3daabaecff34684fd51fac80319d1baad1.zip | |
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.c | 4 |
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; |