[PATCH 3/7] lib/digsig: fix dereference of NULL user_key_payload

[James Morris]

On Thu, 28 Sep 2017, Eric Biggers wrote:

> From: Eric Biggers <ebiggers at google.com>
> 
> 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 at vger.kernel.org>    [v3.3+]
> Signed-off-by: Eric Biggers <ebiggers at google.com>


Reviewed-by: James Morris <james.l.morris at oracle.com>

-- 
James Morris
<jmorris at namei.org>

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