Patch "futex: Add missing error handling to FUTEX_REQUEUE_PI" has been added to the 4.9-stable tree

This is a note to let you know that I've just added the patch titled

futex: Add missing error handling to FUTEX_REQUEUE_PI

to the 4.9-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-add-missing-error-handling-to-futex_requeue_pi.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Peter Zijlstra <[email protected]>
Date: Sat, 4 Mar 2017 10:27:19 +0100
Subject: futex: Add missing error handling to FUTEX_REQUEUE_PI

From: Peter Zijlstra <[email protected]>

commit 9bbb25afeb182502ca4f2c4f3f88af0681b34cae upstream.

Thomas spotted that fixup_pi_state_owner() can return errors and we fail to unlock the rt_mutex in that case.

---
 kernel/futex.c |    2 ++
 1 file changed, 2 insertions(+)

@@ -2896,6 +2896,8 @@ static int futex_wait_requeue_pi(u32 __u
 		if (q.pi_state && (q.pi_state->owner != current)) {
 			spin_lock(q.lock_ptr);
 			ret = fixup_pi_state_owner(uaddr2, &q, current);
+			if (ret && rt_mutex_owner(&q.pi_state->pi_mutex) == current)
+				rt_mutex_unlock(&q.pi_state->pi_mutex);
 			/*
 			 * Drop the reference to the pi state which
 			 * the requeue_pi() code acquired for us.

Patches currently in stable-queue which might be from [email protected] are

queue-4.9/futex-fix-potential-use-after-free-in-futex_requeue_pi.patch queue-4.9/futex-add-missing-error-handling-to-futex_requeue_pi.patch queue-4.9/x86-perf-fix-cr4.pce-propagation-to-use-active_mm-instead-of-mm.patch queue-4.9/locking-rwsem-fix-down_write_killable-for-config_rwsem_generic_spinlock-y.patch queue-4.9/x86-tsc-fix-art-for-tsc_known_freq.patch