On Thu, 28 Sep 2017, Eric Biggers wrote:
> From: Eric Biggers <ebiggers@xxxxxxxxxx>
>
> A key of type "encrypted" references a "master key" which is used to
> encrypt and decrypt the encrypted key's payload. However, when we
> accessed the master key's payload, we failed to handle the case where
> the master key has been revoked, which sets the payload pointer to NULL.
> Note that 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.
>
> This was an issue for master keys of type "user" only. Master keys can
> also be of type "trusted", but those cannot be revoked.
>
> Fixes: 7e70cb497850 ("keys: add new key-type encrypted")
> Cc: <stable@xxxxxxxxxxxxxxx> [v2.6.38+]
> Signed-off-by: Eric Biggers <ebiggers@xxxxxxxxxx>
Reviewed-by: James Morris <james.l.morris@xxxxxxxxxx>
--
James Morris
<jmorris@xxxxxxxxx>