| From | Jiri Slaby <> | Subject | [PATCH 3.12 164/176] KEYS: close race between key lookup and freeing | Date | Wed, 28 Jan 2015 15:29:54 +0100 |
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From: Sasha Levin <sasha.levin@oracle.com>
3.12-stable review patch. If anyone has any objections, please let me know.
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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 <sasha.levin@oracle.com> Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Jiri Slaby <jslaby@suse.cz> --- security/keys/gc.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/security/keys/gc.c b/security/keys/gc.c index d67c97bb1025..797818695c87 100644 --- a/security/keys/gc.c +++ b/security/keys/gc.c @@ -201,12 +201,12 @@ static noinline void key_gc_unused_keys(struct list_head *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 -- 2.2.2
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