This is a note to let you know that I've just added the patch titled
futex-prevent-requeue-pi-on-same-futex.patch futex: Forbid uaddr == uaddr2
in futex_requeue(..., requeue_pi=1)
to the 3.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
futex-prevent-requeue-pi-on-same-futex.patch-futex-forbid-uaddr-uaddr2-in-futex_requeue-...-requeue_pi-1.patch
and it can be found in the queue-3.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.
>From e9c243a5a6de0be8e584c604d353412584b592f8 Mon Sep 17 00:00:00 2001
From: Thomas Gleixner <[email protected]>
Date: Tue, 3 Jun 2014 12:27:06 +0000
Subject: futex-prevent-requeue-pi-on-same-futex.patch futex: Forbid uaddr ==
uaddr2 in futex_requeue(..., requeue_pi=1)
From: Thomas Gleixner <[email protected]>
commit e9c243a5a6de0be8e584c604d353412584b592f8 upstream.
If uaddr == uaddr2, then we have broken the rule of only requeueing from
a non-pi futex to a pi futex with this call. If we attempt this, then
dangling pointers may be left for rt_waiter resulting in an exploitable
condition.
This change brings futex_requeue() in line with futex_wait_requeue_pi()
which performs the same check as per commit 6f7b0a2a5c0f ("futex: Forbid
uaddr == uaddr2 in futex_wait_requeue_pi()")
[ tglx: Compare the resulting keys as well, as uaddrs might be
different depending on the mapping ]
Fixes CVE-2014-3153.
Reported-by: Pinkie Pie
Signed-off-by: Will Drewry <[email protected]>
Signed-off-by: Kees Cook <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Reviewed-by: Darren Hart <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
kernel/futex.c | 25 +++++++++++++++++++++++++
1 file changed, 25 insertions(+)
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -1289,6 +1289,13 @@ static int futex_requeue(u32 __user *uad
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.
*/
@@ -1326,6 +1333,15 @@ retry:
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);
@@ -2357,6 +2373,15 @@ static int futex_wait_requeue_pi(u32 __u
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);
Patches currently in stable-queue which might be from [email protected] are
queue-3.4/futex-always-cleanup-owner-tid-in-unlock_pi.patch
queue-3.4/futex-prevent-requeue-pi-on-same-futex.patch-futex-forbid-uaddr-uaddr2-in-futex_requeue-...-requeue_pi-1.patch
queue-3.4/futex-validate-atomic-acquisition-in-futex_lock_pi_atomic.patch
queue-3.4/futex-add-another-early-deadlock-detection-check.patch
queue-3.4/futex-make-lookup_pi_state-more-robust.patch
queue-3.4/futex-prevent-attaching-to-kernel-threads.patch
queue-3.4/hrtimer-prevent-all-reprogramming-if-hang-detected.patch
queue-3.4/hrtimer-prevent-remote-enqueue-of-leftmost-timers.patch
queue-3.4/hrtimer-set-expiry-time-before-switch_hrtimer_base.patch
queue-3.4/timer-prevent-overflow-in-apply_slack.patch
--
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