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locking/lockdep: Fix possible NULL deref 

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: f52be57080 ("locking/lockdep: Untangle xhlock history save/restore from task independence")
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Peter Zijlstra 2017-12-06 17:32:47 +01:00 committed by Ingo Molnar
parent 328b4ed93b
commit 5e351ad106
1 changed files with 2 additions and 1 deletions
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3
kernel/locking/lockdep.c
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@ -4790,7 +4790,8 @@ 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)