On Thu, 28 Sep 2017, Eric Biggers wrote:
> From: Eric Biggers <ebiggers@xxxxxxxxxx>
>
> When the file /proc/fs/fscache/objects (available with
> CONFIG_FSCACHE_OBJECT_LIST=y) is opened, we request a user key with
> description "fscache:objlist", 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 access its payload.
>
> Fix it by checking for a NULL payload, treating it like a key which was
> already revoked at the time it was requested.
>
> Fixes: 4fbf4291aa15 ("FS-Cache: Allow the current state of all objects to be dumped")
> Cc: <stable@xxxxxxxxxxxxxxx> [v2.6.32+]
> Signed-off-by: Eric Biggers <ebiggers@xxxxxxxxxx>
Reviewed-by: James Morris <james.l.morris@xxxxxxxxxx>
--
James Morris
<jmorris@xxxxxxxxx>