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Date: Tue, 27 Jan 2015 17:27:10 -0800 From: Greg Kroah-Hartman <gregkh@...uxfoundation.org> To: linux-kernel@...r.kernel.org Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>, stable@...r.kernel.org, Sasha Levin <sasha.levin@...cle.com>, David Howells <dhowells@...hat.com> Subject: [PATCH 3.14 32/77] KEYS: close race between key lookup and freeing 3.14-stable review patch. If anyone has any objections, please let me know. ------------------ From: Sasha Levin <sasha.levin@...cle.com> 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@...cle.com> Signed-off-by: David Howells <dhowells@...hat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org> --- security/keys/gc.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- a/security/keys/gc.c +++ b/security/keys/gc.c @@ -157,12 +157,12 @@ 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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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