1 files changed, 87 insertions, 50 deletions

diff --git a/kernel/futex.c b/kernel/futex.c
index 4949d336d88d..e7a35f1039e7 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -150,7 +150,8 @@ static struct futex_hash_bucket *hash_futex(union futex_key *key)
  */
 static inline int match_futex(union futex_key *key1, union futex_key *key2)
 {
-        return (key1->both.word == key2->both.word
+        return (key1 && key2
+                && key1->both.word == key2->both.word
                 && key1->both.ptr == key2->both.ptr
                 && key1->both.offset == key2->both.offset);
 }
@@ -202,8 +203,6 @@ static void drop_futex_key_refs(union futex_key *key)
  * @uaddr:      virtual address of the futex
  * @fshared:    0 for a PROCESS_PRIVATE futex, 1 for PROCESS_SHARED
  * @key:        address where result is stored.
- * @rw:         mapping needs to be read/write (values: VERIFY_READ,
- *              VERIFY_WRITE)
  *
  * Returns a negative error code or 0
  * The key words are stored in *key on success.
@@ -215,7 +214,7 @@ static void drop_futex_key_refs(union futex_key *key)
  * lock_page() might sleep, the caller should not hold a spinlock.
  */
 static int
-get_futex_key(u32 __user *uaddr, int fshared, union futex_key *key, int rw)
+get_futex_key(u32 __user *uaddr, int fshared, union futex_key *key)
 {
         unsigned long address = (unsigned long)uaddr;
         struct mm_struct *mm = current->mm;
@@ -238,7 +237,7 @@ get_futex_key(u32 __user *uaddr, int fshared, union futex_key *key, int rw)
          *        but access_ok() should be faster than find_vma()
          */
         if (!fshared) {
-                if (unlikely(!access_ok(rw, uaddr, sizeof(u32))))
+                if (unlikely(!access_ok(VERIFY_WRITE, uaddr, sizeof(u32))))
                         return -EFAULT;
                 key->private.mm = mm;
                 key->private.address = address;
@@ -247,7 +246,7 @@ get_futex_key(u32 __user *uaddr, int fshared, union futex_key *key, int rw)
         }
 
 again:
-        err = get_user_pages_fast(address, 1, rw == VERIFY_WRITE, &page);
+        err = get_user_pages_fast(address, 1, 1, &page);
         if (err < 0)
                 return err;
 
@@ -303,8 +302,14 @@ void put_futex_key(int fshared, union futex_key *key)
  */
 static int fault_in_user_writeable(u32 __user *uaddr)
 {
-        int ret = get_user_pages(current, current->mm, (unsigned long)uaddr,
-                                 1, 1, 0, NULL, NULL);
+        struct mm_struct *mm = current->mm;
+        int ret;
+
+        down_read(&mm->mmap_sem);
+        ret = get_user_pages(current, mm, (unsigned long)uaddr,
+                             1, 1, 0, NULL, NULL);
+        up_read(&mm->mmap_sem);
+
         return ret < 0 ? ret : 0;
 }
 
@@ -396,9 +401,9 @@ static void free_pi_state(struct futex_pi_state *pi_state)
          * and has cleaned up the pi_state already
          */
         if (pi_state->owner) {
-                spin_lock_irq(&pi_state->owner->pi_lock);
+                raw_spin_lock_irq(&pi_state->owner->pi_lock);
                 list_del_init(&pi_state->list);
-                spin_unlock_irq(&pi_state->owner->pi_lock);
+                raw_spin_unlock_irq(&pi_state->owner->pi_lock);
 
                 rt_mutex_proxy_unlock(&pi_state->pi_mutex, pi_state->owner);
         }
@@ -463,18 +468,18 @@ void exit_pi_state_list(struct task_struct *curr)
          * pi_state_list anymore, but we have to be careful
          * versus waiters unqueueing themselves:
          */
-        spin_lock_irq(&curr->pi_lock);
+        raw_spin_lock_irq(&curr->pi_lock);
         while (!list_empty(head)) {
 
                 next = head->next;
                 pi_state = list_entry(next, struct futex_pi_state, list);
                 key = pi_state->key;
                 hb = hash_futex(&key);
-                spin_unlock_irq(&curr->pi_lock);
+                raw_spin_unlock_irq(&curr->pi_lock);
 
                 spin_lock(&hb->lock);
 
-                spin_lock_irq(&curr->pi_lock);
+                raw_spin_lock_irq(&curr->pi_lock);
                 /*
                  * We dropped the pi-lock, so re-check whether this
                  * task still owns the PI-state:
@@ -488,15 +493,15 @@ void exit_pi_state_list(struct task_struct *curr)
                 WARN_ON(list_empty(&pi_state->list));
                 list_del_init(&pi_state->list);
                 pi_state->owner = NULL;
-                spin_unlock_irq(&curr->pi_lock);
+                raw_spin_unlock_irq(&curr->pi_lock);
 
                 rt_mutex_unlock(&pi_state->pi_mutex);
 
                 spin_unlock(&hb->lock);
 
-                spin_lock_irq(&curr->pi_lock);
+                raw_spin_lock_irq(&curr->pi_lock);
         }
-        spin_unlock_irq(&curr->pi_lock);
+        raw_spin_unlock_irq(&curr->pi_lock);
 }
 
 static int
@@ -525,8 +530,25 @@ lookup_pi_state(u32 uval, struct futex_hash_bucket *hb,
                                 return -EINVAL;
 
                         WARN_ON(!atomic_read(&pi_state->refcount));
-                        WARN_ON(pid && pi_state->owner &&
-                                pi_state->owner->pid != pid);
+
+                        /*
+                         * When pi_state->owner is NULL then the owner died
+                         * and another waiter is on the fly. pi_state->owner
+                         * is fixed up by the task which acquires
+                         * pi_state->rt_mutex.
+                         *
+                         * We do not check for pid == 0 which can happen when
+                         * the owner died and robust_list_exit() cleared the
+                         * TID.
+                         */
+                        if (pid && pi_state->owner) {
+                                /*
+                                 * Bail out if user space manipulated the
+                                 * futex value.
+                                 */
+                                if (pid != task_pid_vnr(pi_state->owner))
+                                        return -EINVAL;
+                        }
 
                         atomic_inc(&pi_state->refcount);
                         *ps = pi_state;
@@ -551,7 +573,7 @@ lookup_pi_state(u32 uval, struct futex_hash_bucket *hb,
          * change of the task flags, we do this protected by
          * p->pi_lock:
          */
-        spin_lock_irq(&p->pi_lock);
+        raw_spin_lock_irq(&p->pi_lock);
         if (unlikely(p->flags & PF_EXITING)) {
                 /*
                  * The task is on the way out. When PF_EXITPIDONE is
@@ -560,7 +582,7 @@ lookup_pi_state(u32 uval, struct futex_hash_bucket *hb,
                  */
                 int ret = (p->flags & PF_EXITPIDONE) ? -ESRCH : -EAGAIN;
 
-                spin_unlock_irq(&p->pi_lock);
+                raw_spin_unlock_irq(&p->pi_lock);
                 put_task_struct(p);
                 return ret;
         }
@@ -579,7 +601,7 @@ lookup_pi_state(u32 uval, struct futex_hash_bucket *hb,
         WARN_ON(!list_empty(&pi_state->list));
         list_add(&pi_state->list, &p->pi_state_list);
         pi_state->owner = p;
-        spin_unlock_irq(&p->pi_lock);
+        raw_spin_unlock_irq(&p->pi_lock);
 
         put_task_struct(p);
 
@@ -753,7 +775,14 @@ static int wake_futex_pi(u32 __user *uaddr, u32 uval, struct futex_q *this)
         if (!pi_state)
                 return -EINVAL;
 
-        spin_lock(&pi_state->pi_mutex.wait_lock);
+        /*
+         * If current does not own the pi_state then the futex is
+         * inconsistent and user space fiddled with the futex value.
+         */
+        if (pi_state->owner != current)
+                return -EINVAL;
+
+        raw_spin_lock(&pi_state->pi_mutex.wait_lock);
         new_owner = rt_mutex_next_owner(&pi_state->pi_mutex);
 
         /*
@@ -782,23 +811,23 @@ static int wake_futex_pi(u32 __user *uaddr, u32 uval, struct futex_q *this)
                 else if (curval != uval)
                         ret = -EINVAL;
                 if (ret) {
-                        spin_unlock(&pi_state->pi_mutex.wait_lock);
+                        raw_spin_unlock(&pi_state->pi_mutex.wait_lock);
                         return ret;
                 }
         }
 
-        spin_lock_irq(&pi_state->owner->pi_lock);
+        raw_spin_lock_irq(&pi_state->owner->pi_lock);
         WARN_ON(list_empty(&pi_state->list));
         list_del_init(&pi_state->list);
-        spin_unlock_irq(&pi_state->owner->pi_lock);
+        raw_spin_unlock_irq(&pi_state->owner->pi_lock);
 
-        spin_lock_irq(&new_owner->pi_lock);
+        raw_spin_lock_irq(&new_owner->pi_lock);
         WARN_ON(!list_empty(&pi_state->list));
         list_add(&pi_state->list, &new_owner->pi_state_list);
         pi_state->owner = new_owner;
-        spin_unlock_irq(&new_owner->pi_lock);
+        raw_spin_unlock_irq(&new_owner->pi_lock);
 
-        spin_unlock(&pi_state->pi_mutex.wait_lock);
+        raw_spin_unlock(&pi_state->pi_mutex.wait_lock);
         rt_mutex_unlock(&pi_state->pi_mutex);
 
         return 0;
@@ -860,7 +889,7 @@ static int futex_wake(u32 __user *uaddr, int fshared, int nr_wake, u32 bitset)
         if (!bitset)
                 return -EINVAL;
 
-        ret = get_futex_key(uaddr, fshared, &key, VERIFY_READ);
+        ret = get_futex_key(uaddr, fshared, &key);
         if (unlikely(ret != 0))
                 goto out;
 
@@ -906,10 +935,10 @@ futex_wake_op(u32 __user *uaddr1, int fshared, u32 __user *uaddr2,
         int ret, op_ret;
 
 retry:
-        ret = get_futex_key(uaddr1, fshared, &key1, VERIFY_READ);
+        ret = get_futex_key(uaddr1, fshared, &key1);
         if (unlikely(ret != 0))
                 goto out;
-        ret = get_futex_key(uaddr2, fshared, &key2, VERIFY_WRITE);
+        ret = get_futex_key(uaddr2, fshared, &key2);
         if (unlikely(ret != 0))
                 goto out_put_key1;
 
@@ -1003,7 +1032,7 @@ void requeue_futex(struct futex_q *q, struct futex_hash_bucket *hb1,
                 plist_add(&q->list, &hb2->chain);
                 q->lock_ptr = &hb2->lock;
 #ifdef CONFIG_DEBUG_PI_LIST
-                q->list.plist.lock = &hb2->lock;
+                q->list.plist.spinlock = &hb2->lock;
 #endif
         }
         get_futex_key_refs(key2);
@@ -1028,7 +1057,6 @@ static inline
 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);
         q->key = *key;
 
@@ -1040,7 +1068,7 @@ void requeue_pi_wake_futex(struct futex_q *q, union futex_key *key,
 
         q->lock_ptr = &hb->lock;
 #ifdef CONFIG_DEBUG_PI_LIST
-        q->list.plist.lock = &hb->lock;
+        q->list.plist.spinlock = &hb->lock;
 #endif
 
         wake_up_state(q->task, TASK_NORMAL);
@@ -1169,11 +1197,10 @@ retry:
                 pi_state = NULL;
         }
 
-        ret = get_futex_key(uaddr1, fshared, &key1, VERIFY_READ);
+        ret = get_futex_key(uaddr1, fshared, &key1);
         if (unlikely(ret != 0))
                 goto out;
-        ret = get_futex_key(uaddr2, fshared, &key2,
-                            requeue_pi ? VERIFY_WRITE : VERIFY_READ);
+        ret = get_futex_key(uaddr2, fshared, &key2);
         if (unlikely(ret != 0))
                 goto out_put_key1;
 
@@ -1226,6 +1253,7 @@ retry_private:
                  */
                 if (ret == 1) {
                         WARN_ON(pi_state);
+                        drop_count++;
                         task_count++;
                         ret = get_futex_value_locked(&curval2, uaddr2);
                         if (!ret)
@@ -1304,6 +1332,7 @@ retry_private:
                         if (ret == 1) {
                                 /* We got the lock. */
                                 requeue_pi_wake_futex(this, &key2, hb2);
+                                drop_count++;
                                 continue;
                         } else if (ret) {
                                 /* -EDEADLK */
@@ -1386,7 +1415,7 @@ static inline void queue_me(struct futex_q *q, struct futex_hash_bucket *hb)
 
         plist_node_init(&q->list, prio);
 #ifdef CONFIG_DEBUG_PI_LIST
-        q->list.plist.lock = &hb->lock;
+        q->list.plist.spinlock = &hb->lock;
 #endif
         plist_add(&q->list, &hb->chain);
         q->task = current;
@@ -1521,18 +1550,18 @@ retry:
          * itself.
          */
         if (pi_state->owner != NULL) {
-                spin_lock_irq(&pi_state->owner->pi_lock);
+                raw_spin_lock_irq(&pi_state->owner->pi_lock);
                 WARN_ON(list_empty(&pi_state->list));
                 list_del_init(&pi_state->list);
-                spin_unlock_irq(&pi_state->owner->pi_lock);
+                raw_spin_unlock_irq(&pi_state->owner->pi_lock);
         }
 
         pi_state->owner = newowner;
 
-        spin_lock_irq(&newowner->pi_lock);
+        raw_spin_lock_irq(&newowner->pi_lock);
         WARN_ON(!list_empty(&pi_state->list));
         list_add(&pi_state->list, &newowner->pi_state_list);
-        spin_unlock_irq(&newowner->pi_lock);
+        raw_spin_unlock_irq(&newowner->pi_lock);
         return 0;
 
         /*
@@ -1730,7 +1759,7 @@ static int futex_wait_setup(u32 __user *uaddr, u32 val, int fshared,
          */
 retry:
         q->key = FUTEX_KEY_INIT;
-        ret = get_futex_key(uaddr, fshared, &q->key, VERIFY_READ);
+        ret = get_futex_key(uaddr, fshared, &q->key);
         if (unlikely(ret != 0))
                 return ret;
 
@@ -1791,6 +1820,7 @@ static int futex_wait(u32 __user *uaddr, int fshared,
                                              current->timer_slack_ns);
         }
 
+retry:
         /* Prepare to wait on uaddr. */
         ret = futex_wait_setup(uaddr, val, fshared, &q, &hb);
         if (ret)
@@ -1808,9 +1838,14 @@ static int futex_wait(u32 __user *uaddr, int fshared,
                 goto out_put_key;
 
         /*
-         * We expect signal_pending(current), but another thread may
-         * have handled it for us already.
+         * We expect signal_pending(current), but we might be the
+         * victim of a spurious wakeup as well.
          */
+        if (!signal_pending(current)) {
+                put_futex_key(fshared, &q.key);
+                goto retry;
+        }
+
         ret = -ERESTARTSYS;
         if (!abs_time)
                 goto out_put_key;
@@ -1890,7 +1925,7 @@ static int futex_lock_pi(u32 __user *uaddr, int fshared,
         q.requeue_pi_key = NULL;
 retry:
         q.key = FUTEX_KEY_INIT;
-        ret = get_futex_key(uaddr, fshared, &q.key, VERIFY_WRITE);
+        ret = get_futex_key(uaddr, fshared, &q.key);
         if (unlikely(ret != 0))
                 goto out;
 
@@ -1960,7 +1995,7 @@ retry_private:
         /* Unqueue and drop the lock */
         unqueue_me_pi(&q);
 
-        goto out;
+        goto out_put_key;
 
 out_unlock_put_key:
         queue_unlock(&q, hb);
@@ -2009,7 +2044,7 @@ retry:
         if ((uval & FUTEX_TID_MASK) != task_pid_vnr(current))
                 return -EPERM;
 
-        ret = get_futex_key(uaddr, fshared, &key, VERIFY_WRITE);
+        ret = get_futex_key(uaddr, fshared, &key);
         if (unlikely(ret != 0))
                 goto out;
 
@@ -2118,9 +2153,11 @@ int handle_early_requeue_pi_wakeup(struct futex_hash_bucket *hb,
                  */
                 plist_del(&q->list, &q->list.plist);
 
+                /* Handle spurious wakeups gracefully */
+                ret = -EWOULDBLOCK;
                 if (timeout && !timeout->task)
                         ret = -ETIMEDOUT;
-                else
+                else if (signal_pending(current))
                         ret = -ERESTARTNOINTR;
         }
         return ret;
@@ -2199,7 +2236,7 @@ static int futex_wait_requeue_pi(u32 __user *uaddr, int fshared,
         rt_waiter.task = NULL;
 
         key2 = FUTEX_KEY_INIT;
-        ret = get_futex_key(uaddr2, fshared, &key2, VERIFY_WRITE);
+        ret = get_futex_key(uaddr2, fshared, &key2);
         if (unlikely(ret != 0))
                 goto out;