futex: Forbid uaddr == uaddr2 in futex_requeue(...,
requeue_pi=1) (bnc#880892 CVE-2014-3153).
suse-commit: ed731a40f3338312762aaf039a73ab0852edefd2
diff --git a/kernel/futex.c b/kernel/futex.c
index b1a1842..c1d6271 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -1387,6 +1387,13 @@
if (requeue_pi) {
/*
+ * Requeue PI only works on two distinct uaddrs. This
+ * check is only valid for private futexes. See below.
+ */
+ if (uaddr1 == uaddr2)
+ return -EINVAL;
+
+ /*
* requeue_pi requires a pi_state, try to allocate it now
* without any locks in case it fails.
*/
@@ -1424,6 +1431,15 @@
if (unlikely(ret != 0))
goto out_put_key1;
+ /*
+ * The check above which compares uaddrs is not sufficient for
+ * shared futexes. We need to compare the keys:
+ */
+ if (requeue_pi && match_futex(&key1, &key2)) {
+ ret = -EINVAL;
+ goto out_put_keys;
+ }
+
hb1 = hash_futex(&key1);
hb2 = hash_futex(&key2);
@@ -2442,6 +2458,15 @@
if (ret)
goto out_key2;
+ /*
+ * The check above which compares uaddrs is not sufficient for
+ * shared futexes. We need to compare the keys:
+ */
+ if (match_futex(&q.key, &key2)) {
+ ret = -EINVAL;
+ goto out_put_keys;
+ }
+
/* Queue the futex_q, drop the hb lock, wait for wakeup. */
futex_wait_queue_me(hb, &q, to);
