[PATCH AUTOSEL for 4.14 060/100] locking/lockdep: Fix possible NULL deref

Sasha Levin
2018-01-28T22:27:12Z

From: Peter Zijlstra <peterz@infradead.org>

[ Upstream commit 5e351ad106997e06b2dc3da9c6b939b95f67fb88 ]

We can't invalidate xhlocks when we've not yet allocated any.

Reported-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Fixes: f52be5708076 ("locking/lockdep: Untangle xhlock history save/restore from task independence")
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
---
kernel/locking/lockdep.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index e36e652d996f..dae0d06422a1 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -4780,7 +4780,8 @@ void lockdep_invariant_state(bool force)
* Verify the former, enforce the latter.
*/
WARN_ON_ONCE(!force && current->lockdep_depth);
- invalidate_xhlock(&xhlock(current->xhlock_idx));
+ if (current->xhlocks)
+ invalidate_xhlock(&xhlock(current->xhlock_idx));
}

static int cross_lock(struct lockdep_map *lock)
--
2.11.0