[ 120/122] futex: Test for pi_mutex on fault in futex_wait_requeue_pi()

From: Greg Kroah-Hartman
Date: Tue Aug 07 2012 - 18:33:57 EST


From: Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx>

3.5-stable review patch. If anyone has any objections, please let me know.

------------------

From: Darren Hart <dvhart@xxxxxxxxxxxxxxx>

commit b6070a8d9853eda010a549fa9a09eb8d7269b929 upstream.

If fixup_pi_state_owner() faults, pi_mutex may be NULL. Test
for pi_mutex != NULL before testing the owner against current
and possibly unlocking it.

Signed-off-by: Darren Hart <dvhart@xxxxxxxxxxxxxxx>
Cc: Dave Jones <davej@xxxxxxxxxx>
Cc: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Link: http://lkml.kernel.org/r/dc59890338fc413606f04e5c5b131530734dae3d.1342809673.git.dvhart@xxxxxxxxxxxxxxx
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
kernel/futex.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -2370,7 +2370,7 @@ static int futex_wait_requeue_pi(u32 __u
* fault, unlock the rt_mutex and return the fault to userspace.
*/
if (ret == -EFAULT) {
- if (rt_mutex_owner(pi_mutex) == current)
+ if (pi_mutex && rt_mutex_owner(pi_mutex) == current)
rt_mutex_unlock(pi_mutex);
} else if (ret == -EINTR) {
/*


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