]> git.proxmox.com Git - mirror_ubuntu-disco-kernel.git/commit
futex: Fix handling of bad requeue syscall pairing
authorDarren Hart <dvhltc@us.ibm.com>
Fri, 7 Aug 2009 22:20:48 +0000 (15:20 -0700)
committerIngo Molnar <mingo@elte.hu>
Mon, 10 Aug 2009 18:38:11 +0000 (20:38 +0200)
commit392741e0a4e17c82e3978b7fcbf04291294dc0a1
treec58437276d5eae05c46b3739d9bece01e357e6e2
parent4dc88029fd916b860ef063c40180aa604ce93494
futex: Fix handling of bad requeue syscall pairing

If futex_requeue(requeue_pi=1) finds a futex_q that was created by a call
other the futex_wait_requeue_pi(), the q.rt_waiter may be null.  If so,
this will result in an oops from the following call graph:

futex_requeue()
  rt_mutex_start_proxy_lock()
    task_blocks_on_rt_mutex()
      waiter->task dereference
        OOPS

We currently WARN_ON() if this is detected, clearly this is inadequate.
If we detect a mispairing in futex_requeue(), bail out, seding -EINVAL to
user-space.

V2: Fix parenthesis warnings.

Signed-off-by: Darren Hart <dvhltc@us.ibm.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: John Kacur <jkacur@redhat.com>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Dinakar Guniguntala <dino@in.ibm.com>
Cc: John Stultz <johnstul@linux.vnet.ibm.com>
LKML-Reference: <4A7CA8C0.7010809@us.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
kernel/futex.c