2009-10-14 17:13:44

by Darren Hart

Subject: [PATCH] futex: check for NULL keys in match_futex

From: Darren Hart <[email protected]>

If userspace tries to perform a requeue_pi on a non-requeue_pi waiter, it
will find the futex_q->requeue_pi_key to be NULL and OOPS. Check for NULL
in match_futex(). This results in cleaner code than checking at each call
site. While match_futex(NULL, NULL) returning false is a little odd, it
will OOPS as it is today. This approach catches all possible call sites
as well.

Signed-off-by: Darren Hart <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Ingo Molnar <[email protected]>
CC: Eric Dumazet <[email protected]>
CC: Dinakar Guniguntala <[email protected]>
CC: John Stultz <[email protected]>
---

kernel/futex.c | 3 ++-
1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/kernel/futex.c b/kernel/futex.c
index 4949d33..5971730 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -150,7 +150,8 @@ static struct futex_hash_bucket *hash_futex(union futex_key *key)
*/
static inline int match_futex(union futex_key *key1, union futex_key *key2)
{
- return (key1->both.word == key2->both.word
+ return (key1 && key2
+ && key1->both.word == key2->both.word
&& key1->both.ptr == key2->both.ptr
&& key1->both.offset == key2->both.offset);
}
--
Darren Hart
IBM Linux Technology Center
Real-Time Linux Team

2009-10-14 20:13:39

by Darren Hart

Subject: [tip:core/urgent] futex: Check for NULL keys in match_futex

Commit-ID: 2bc872036e1c5948b5b02942810bbdd8dbdb9812
Gitweb: http://git.kernel.org/tip/2bc872036e1c5948b5b02942810bbdd8dbdb9812
Author: Darren Hart <[email protected]>
AuthorDate: Wed, 14 Oct 2009 10:12:39 -0700
Committer: Thomas Gleixner <[email protected]>
CommitDate: Wed, 14 Oct 2009 22:00:14 +0200

futex: Check for NULL keys in match_futex

If userspace tries to perform a requeue_pi on a non-requeue_pi waiter,
it will find the futex_q->requeue_pi_key to be NULL and OOPS.

Check for NULL in match_futex() instead of doing explicit NULL pointer
checks on all call sites. While match_futex(NULL, NULL) returning
false is a little odd, it's still correct as we expect valid key
references.

Signed-off-by: Darren Hart <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Ingo Molnar <[email protected]>
CC: Eric Dumazet <[email protected]>
CC: Dinakar Guniguntala <[email protected]>
CC: John Stultz <[email protected]>
Cc: [email protected]
LKML-Reference: <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
---
kernel/futex.c | 3 ++-
1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/kernel/futex.c b/kernel/futex.c
index 5c88839..06938e5 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -150,7 +150,8 @@ static struct futex_hash_bucket *hash_futex(union futex_key *key)
*/
static inline int match_futex(union futex_key *key1, union futex_key *key2)
{
- return (key1->both.word == key2->both.word
+ return (key1 && key2
+ && key1->both.word == key2->both.word
&& key1->both.ptr == key2->both.ptr
&& key1->both.offset == key2->both.offset);
}