[05/07] [PATCH] Fix reproducible SMP crash in security/keys/key.c

From: Greg KH
Date: Wed Apr 27 2005 - 12:27:48 EST

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


Jani Jaakkola <jjaakkol@xxxxxxxxxxxxxx> wrote:
> SMP race handling is broken in key_user_lookup() in security/keys/key.c

This was fixed post-2.6.11. Can you confirm that 2.6.12-rc2 works OK?

This is the patch we used. It should go into -stable if it's not already

From: Alexander Nyberg <alexn@xxxxxxxxx>

I looked at some of the oops reports against keyrings, I think the problem
is that the search isn't restarted after dropping the key_user_lock, *p
will still be NULL when we get back to try_again and look through the tree.

It looks like the intention was that the search start over from scratch.

Signed-off-by: Alexander Nyberg <alexn@xxxxxxxxx>
Cc: David Howells <dhowells@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
Signed-off-by: Chris Wright <chrisw@xxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

25-akpm/security/keys/key.c | 3 ++-
1 files changed, 2 insertions(+), 1 deletion(-)

diff -puN security/keys/key.c~race-against-parent-deletion-in-key_user_lookup security/keys/key.c
--- 25/security/keys/key.c~race-against-parent-deletion-in-key_user_lookup 2005-03-10 00:38:38.000000000 -0800
+++ 25-akpm/security/keys/key.c 2005-03-10 00:38:38.000000000 -0800
@@ -57,9 +57,10 @@ struct key_user *key_user_lookup(uid_t u
struct key_user *candidate = NULL, *user;
struct rb_node *parent = NULL;
- struct rb_node **p = &key_user_tree.rb_node;
+ struct rb_node **p;

+ p = &key_user_tree.rb_node;

/* search the tree for a user record with a matching UID */
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/