On Thu, 28 Sep 2017, Eric Biggers wrote:
> From: Eric Biggers <ebiggers@xxxxxxxxxx>
>
> When an fscrypt-encrypted file is opened, we request the file's master
> key from the keyrings service as a logon key, then access 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: 88bd6ccdcdd6 ("ext4 crypto: add encryption key management facilities")
> Cc: <stable@xxxxxxxxxxxxxxx> [v4.1+]
> Signed-off-by: Eric Biggers <ebiggers@xxxxxxxxxx>
Reviewed-by: James Morris <james.l.morris@xxxxxxxxxx>
--
James Morris
<jmorris@xxxxxxxxx>