1 files changed, 22 insertions, 6 deletions

diff --git a/kernel/futex.c b/kernel/futex.c
index 0672ff88f159..e18cfbdc7190 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -1010,15 +1010,19 @@ void requeue_futex(struct futex_q *q, struct futex_hash_bucket *hb1,
  * requeue_pi_wake_futex() - Wake a task that acquired the lock during requeue
  * q:   the futex_q
  * key: the key of the requeue target futex
+ * hb:  the hash_bucket of the requeue target futex
  *
  * During futex_requeue, with requeue_pi=1, it is possible to acquire the
  * target futex if it is uncontended or via a lock steal.  Set the futex_q key
  * to the requeue target futex so the waiter can detect the wakeup on the right
  * futex, but remove it from the hb and NULL the rt_waiter so it can detect
- * atomic lock acquisition.  Must be called with the q->lock_ptr held.
+ * atomic lock acquisition.  Set the q->lock_ptr to the requeue target hb->lock
+ * to protect access to the pi_state to fixup the owner later.  Must be called
+ * with both q->lock_ptr and hb->lock held.
  */
 static inline
-void requeue_pi_wake_futex(struct futex_q *q, union futex_key *key)
+void requeue_pi_wake_futex(struct futex_q *q, union futex_key *key,
+                           struct futex_hash_bucket *hb)
 {
         drop_futex_key_refs(&q->key);
         get_futex_key_refs(key);
@@ -1030,6 +1034,11 @@ void requeue_pi_wake_futex(struct futex_q *q, union futex_key *key)
         WARN_ON(!q->rt_waiter);
         q->rt_waiter = NULL;
 
+        q->lock_ptr = &hb->lock;
+#ifdef CONFIG_DEBUG_PI_LIST
+        q->list.plist.lock = &hb->lock;
+#endif
+
         wake_up_state(q->task, TASK_NORMAL);
 }
 
@@ -1088,7 +1097,7 @@ static int futex_proxy_trylock_atomic(u32 __user *pifutex,
         ret = futex_lock_pi_atomic(pifutex, hb2, key2, ps, top_waiter->task,
                                    set_waiters);
         if (ret == 1)
-                requeue_pi_wake_futex(top_waiter, key2);
+                requeue_pi_wake_futex(top_waiter, key2, hb2);
 
         return ret;
 }
@@ -1247,8 +1256,15 @@ retry_private:
                 if (!match_futex(&this->key, &key1))
                         continue;
 
-                WARN_ON(!requeue_pi && this->rt_waiter);
-                WARN_ON(requeue_pi && !this->rt_waiter);
+                /*
+                 * FUTEX_WAIT_REQEUE_PI and FUTEX_CMP_REQUEUE_PI should always
+                 * be paired with each other and no other futex ops.
+                 */
+                if ((requeue_pi && !this->rt_waiter) ||
+                    (!requeue_pi && this->rt_waiter)) {
+                        ret = -EINVAL;
+                        break;
+                }
 
                 /*
                  * Wake nr_wake waiters.  For requeue_pi, if we acquired the
@@ -1273,7 +1289,7 @@ retry_private:
                                                         this->task, 1);
                         if (ret == 1) {
                                 /* We got the lock. */
-                                requeue_pi_wake_futex(this, &key2);
+                                requeue_pi_wake_futex(this, &key2, hb2);
                                 continue;
                         } else if (ret) {
                                 /* -EDEADLK */