This is a note to let you know that I've just added the patch titled
futex: Unlock hb->lock in futex_wait_requeue_pi() error path
to the 3.16-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
futex-unlock-hb-lock-in-futex_wait_requeue_pi-error-path.patch
and it can be found in the queue-3.16 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 13c42c2f43b19aab3195f2d357db00d1e885eaa8 Mon Sep 17 00:00:00 2001
From: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Date: Thu, 11 Sep 2014 23:44:35 +0200
Subject: futex: Unlock hb->lock in futex_wait_requeue_pi() error path
From: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
commit 13c42c2f43b19aab3195f2d357db00d1e885eaa8 upstream.
futex_wait_requeue_pi() calls futex_wait_setup(). If
futex_wait_setup() succeeds it returns with hb->lock held and
preemption disabled. Now the sanity check after this does:
if (match_futex(&q.key, &key2)) {
ret = -EINVAL;
goto out_put_keys;
}
which releases the keys but does not release hb->lock.
So we happily return to user space with hb->lock held and therefor
preemption disabled.
Unlock hb->lock before taking the exit route.
Reported-by: Dave "Trinity" Jones <davej@xxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Reviewed-by: Darren Hart <dvhart@xxxxxxxxxxxxxxx>
Reviewed-by: Davidlohr Bueso <dave@xxxxxxxxxxxx>
Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1409112318500.4178@nanos
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
kernel/futex.c | 1 +
1 file changed, 1 insertion(+)
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -2628,6 +2628,7 @@ static int futex_wait_requeue_pi(u32 __u
* shared futexes. We need to compare the keys:
*/
if (match_futex(&q.key, &key2)) {
+ queue_unlock(hb);
ret = -EINVAL;
goto out_put_keys;
}
Patches currently in stable-queue which might be from tglx@xxxxxxxxxxxxx are
queue-3.16/futex-unlock-hb-lock-in-futex_wait_requeue_pi-error-path.patch
queue-3.16/arm-8133-1-use-irq_set_affinity-with-force-false-when-migrating-irqs.patch
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