This is a note to let you know that I've just added the patch titled
KEYS: close race between key lookup and freeing
to the 3.18-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
keys-close-race-between-key-lookup-and-freeing.patch
and it can be found in the queue-3.18 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.
>From a3a8784454692dd72e5d5d34dcdab17b4420e74c Mon Sep 17 00:00:00 2001
From: Sasha Levin <[email protected]>
Date: Mon, 29 Dec 2014 09:39:01 -0500
Subject: KEYS: close race between key lookup and freeing
From: Sasha Levin <[email protected]>
commit a3a8784454692dd72e5d5d34dcdab17b4420e74c upstream.
When a key is being garbage collected, it's key->user would get put before
the ->destroy() callback is called, where the key is removed from it's
respective tracking structures.
This leaves a key hanging in a semi-invalid state which leaves a window open
for a different task to try an access key->user. An example is
find_keyring_by_name() which would dereference key->user for a key that is
in the process of being garbage collected (where key->user was freed but
->destroy() wasn't called yet - so it's still present in the linked list).
This would cause either a panic, or corrupt memory.
Fixes CVE-2014-9529.
Signed-off-by: Sasha Levin <[email protected]>
Signed-off-by: David Howells <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
security/keys/gc.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
--- a/security/keys/gc.c
+++ b/security/keys/gc.c
@@ -148,12 +148,12 @@ static noinline void key_gc_unused_keys(
if (test_bit(KEY_FLAG_INSTANTIATED, &key->flags))
atomic_dec(&key->user->nikeys);
- key_user_put(key->user);
-
/* now throw away the key memory */
if (key->type->destroy)
key->type->destroy(key);
+ key_user_put(key->user);
+
kfree(key->description);
#ifdef KEY_DEBUGGING
Patches currently in stable-queue which might be from [email protected] are
queue-3.18/keys-close-race-between-key-lookup-and-freeing.patch
queue-3.18/time-adjtimex-validate-the-adj_frequency-values.patch
queue-3.18/time-settimeofday-validate-the-values-of-tv-from-user.patch
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