From d694ad62bf539dbb20a0899ac2a954555f9e4a83 Mon Sep 17 00:00:00 2001
From: Manfred Spraul <manfred@colorfullife.com>
Date: Mon, 25 Jul 2011 17:11:47 -0700
Subject: [PATCH] ipc/sem.c: fix race with concurrent semtimedop() timeouts and
 IPC_RMID

If a semaphore array is removed and in parallel a sleeping task is woken
up (signal or timeout, does not matter), then the woken up task does not
wait until wake_up_sem_queue_do() is completed.  This will cause crashes,
because wake_up_sem_queue_do() will read from a stale pointer.

The fix is simple: Regardless of anything, always call get_queue_result().
This function waits until wake_up_sem_queue_do() has finished it's task.

Addresses https://bugzilla.kernel.org/show_bug.cgi?id=27142

Reported-by: Yuriy Yevtukhov <yuriy@ucoz.com>
Reported-by: Harald Laabs <kernel@dasr.de>
Signed-off-by: Manfred Spraul <manfred@colorfullife.com>
Acked-by: Eric Dumazet <eric.dumazet@gmail.com>
Cc: <stable@kernel.org>		[2.6.35+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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