Eric Lee / smarc-ti-linux-kernel

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Commit e9c243a5a6de0be8e584c604d353412584b592f8

Authored by Thomas Gleixner
Committed by Linus Torvalds
1 parent fad01e866a
Exists in ti-lsk-linux-4.1.y and in 12 other branches dlt-processor-sdk-linux-03.00.00.04, processor-sdk-linux-02.00.01, smarc-ti-linux-3.15.y, smarc-ti-lsk-linux-4.1.y, smarct3x-processor-sdk-04.01.00.06, smarct3x-processor-sdk-linux-02.00.01, smarct3x-processor-sdk-linux-03.00.00.04, smarct4x-800-processor-sdk-linux-02.00.01, smarct4x-processor-sdk-04.01.00.06, smarct4x-processor-sdk-linux-02.00.01, smarct4x-processor-sdk-linux-03.00.00.04, ti-linux-3.15.y

futex-prevent-requeue-pi-on-same-futex.patch futex: Forbid uaddr == uaddr2 in fu… 

…tex_requeue(..., requeue_pi=1)

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 <wad@chromium.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: stable@vger.kernel.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Darren Hart <dvhart@linux.intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Showing 1 changed file with 25 additions and 0 deletions Side-by-side Diff

... ... @@ -1442,6 +1442,13 @@
1442 1442  
1443 1443 if (requeue_pi) {
1444 1444 /*
  1445 + * Requeue PI only works on two distinct uaddrs. This
  1446 + * check is only valid for private futexes. See below.
  1447 + */
  1448 + if (uaddr1 == uaddr2)
  1449 + return -EINVAL;
  1450 +
  1451 + /*
1445 1452 * requeue_pi requires a pi_state, try to allocate it now
1446 1453 * without any locks in case it fails.
1447 1454 */
... ... @@ -1479,6 +1486,15 @@
1479 1486 if (unlikely(ret != 0))
1480 1487 goto out_put_key1;
1481 1488  
  1489 + /*
  1490 + * The check above which compares uaddrs is not sufficient for
  1491 + * shared futexes. We need to compare the keys:
  1492 + */
  1493 + if (requeue_pi && match_futex(&key1, &key2)) {
  1494 + ret = -EINVAL;
  1495 + goto out_put_keys;
  1496 + }
  1497 +
1482 1498 hb1 = hash_futex(&key1);
1483 1499 hb2 = hash_futex(&key2);
1484 1500  
... ... @@ -2524,6 +2540,15 @@
2524 2540 ret = futex_wait_setup(uaddr, val, flags, &q, &hb);
2525 2541 if (ret)
2526 2542 goto out_key2;
  2543 +
  2544 + /*
  2545 + * The check above which compares uaddrs is not sufficient for
  2546 + * shared futexes. We need to compare the keys:
  2547 + */
  2548 + if (match_futex(&q.key, &key2)) {
  2549 + ret = -EINVAL;
  2550 + goto out_put_keys;
  2551 + }
2527 2552  
2528 2553 /* Queue the futex_q, drop the hb lock, wait for wakeup. */
2529 2554 futex_wait_queue_me(hb, &q, to);