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

Jani Jaakkola <jjaakkol@cs.Helsinki.FI> 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
there.

From: Alexander Nyberg <alexn@dsv.su.se>

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@dsv.su.se>
Cc: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Chris Wright <chrisw@osdl.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
akpm@osdl.org 2005-04-29 18:01:08 -07:00 committed by Greg KH
parent 64ffae4fd8
commit 4b4f0b12c4
1 changed files with 2 additions and 1 deletions
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3
security/keys/key.c
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@ -57,9 +57,10 @@ struct key_user *key_user_lookup(uid_t uid)
{
struct key_user *candidate = NULL, *user;
struct rb_node *parent = NULL;
struct rb_node **p = &key_user_tree.rb_node;
struct rb_node **p;
try_again:
p = &key_user_tree.rb_node;
spin_lock(&key_user_lock);
/* search the tree for a user record with a matching UID */