1 files changed, 39 insertions, 18 deletions

diff --git a/kernel/futex.c b/kernel/futex.c
index 8e3c3ffe1b9a..e7a35f1039e7 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -203,8 +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.
@@ -216,7 +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;
@@ -239,7 +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;
@@ -248,7 +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;
 
@@ -532,8 +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;
@@ -760,6 +775,13 @@ static int wake_futex_pi(u32 __user *uaddr, u32 uval, struct futex_q *this)
         if (!pi_state)
                 return -EINVAL;
 
+        /*
+         * 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);
 
@@ -867,7 +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;
 
@@ -913,10 +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;
 
@@ -1175,11 +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;
 
@@ -1738,7 +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;
 
@@ -1904,7 +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;
 
@@ -1974,7 +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);
@@ -2023,7 +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;
 
@@ -2215,7 +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;