locking/lockdep: Fix possible NULL deref

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

Reported-by: Dmitry Vyukov <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: [email protected]
Fixes: f52be5708076 ("locking/lockdep: Untangle xhlock history save/restore from task independence")
Signed-off-by: Ingo Molnar <[email protected]>

diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index 9776da8db180d63c94f0a698bac844e91c24c0ce..670d8d7d8087ccabb8d9fe2c8397134d1559bcd8 100644 (file)
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -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)