Eric Biggers f9e7e2d605 lib/digsig: fix dereference of NULL user_key_payload
commit 192cabd6a296cbc57b3d8c05c4c89d87fc102506 upstream.

digsig_verify() requests a user key, then accesses its payload.
However, a revoked key has a NULL payload, and we failed to check for
this.  request_key() *does* skip revoked keys, but there is still a
window where the key can be revoked before we acquire its semaphore.

Fix it by checking for a NULL payload, treating it like a key which was
already revoked at the time it was requested.

Fixes: 051dbb918c7f ("crypto: digital signature verification support")
Reviewed-by: James Morris <james.l.morris@oracle.com>
Cc: Dmitry Kasatkin <dmitry.kasatkin@intel.com>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-10-27 10:38:08 +02:00
..
2014-10-09 11:35:48 +03:00
2017-09-02 07:07:54 +02:00
2016-10-11 15:06:30 -07:00
2015-11-23 09:44:58 +01:00
2016-03-17 15:09:34 -07:00
2016-02-07 23:17:59 -08:00
2016-10-06 17:13:54 -07:00
2014-04-30 19:49:37 +01:00
2014-08-06 18:01:25 -07:00
2014-05-05 09:09:14 +02:00
2017-04-21 09:31:21 +02:00
2016-05-23 17:04:14 -07:00
2014-08-08 15:57:25 -07:00
2016-03-09 15:43:42 -08:00
2015-02-12 18:54:15 -08:00
2014-06-25 17:45:43 -07:00
2016-04-23 20:13:24 -04:00
2015-09-08 14:35:59 -07:00
2015-02-12 18:54:16 -08:00
2016-07-06 10:51:14 +01:00
2016-09-20 04:43:36 -04:00
2016-09-19 08:19:40 -06:00
2015-03-23 22:12:08 -04:00
2015-06-25 17:00:40 -07:00
2016-03-17 15:09:34 -07:00
2016-05-30 15:26:57 -07:00
2016-08-02 17:31:41 -04:00