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Cong Wang 89e4078c6e mqueue: fix a use-after-free in sys_mq_notify()
[ Upstream commit f991af3daabaecff34684fd51fac80319d1baad1 ]

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>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
2017-07-31 13:37:53 -04:00
..
2014-06-06 16:08:14 -07:00
2014-10-14 02:18:23 +02:00
2016-08-19 23:08:33 -04:00
2016-08-19 23:08:33 -04:00
2014-06-06 16:08:14 -07:00