On Thu, 28 Sep 2017, Eric Biggers wrote:
> From: Eric Biggers <ebiggers@xxxxxxxxxx>
>
> 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")
> Cc: <stable@xxxxxxxxxxxxxxx> [v3.3+]
> Signed-off-by: Eric Biggers <ebiggers@xxxxxxxxxx>
Reviewed-by: James Morris <james.l.morris@xxxxxxxxxx>
--
James Morris
<jmorris@xxxxxxxxx>