futex-prevent-requeue-pi-on-same-futex.patch futex: Forbid uaddr == uaddr2 in futex_r...
authorThomas Gleixner <tglx@linutronix.de>
Tue, 3 Jun 2014 12:27:06 +0000 (12:27 +0000)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Sat, 7 Jun 2014 23:02:16 +0000 (16:02 -0700)
commit4cca4db7bd5fb663660da34a3514d9fa8f5f14f3
tree31514f38e1694d440f616b23b91ac9686bbc91ed
parentc6f9d698ffd5cfbb941177bec02b43542c748d77
futex-prevent-requeue-pi-on-same-futex.patch futex: Forbid uaddr == uaddr2 in futex_requeue(..., requeue_pi=1)

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 <wad@chromium.org>
Signed-off-by: Kees Cook <keescook@chromium.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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
kernel/futex.c