[PATCH 1/7] KEYS: encrypted: fix dereference of NULL user_key_payload

[James Morris]

On Thu, 28 Sep 2017, Eric Biggers wrote:

> From: Eric Biggers <ebiggers at google.com>
> 
> 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 the master key has been revoked, which sets the payload pointer to NULL.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 at vger.kernel.org>    [v2.6.38+]
> 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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