Re: [v2.6.34-stable 71/77] crypto: ghash - Avoid null pointer dereference if no key is set

Paul Gortmaker
2013-01-09T14:57:23Z

On 13-01-08 09:56 PM, Nick Bowler wrote:
> On 2013-01-08 18:35 -0500, Paul Gortmaker wrote:
>> From: Nick Bowler <nbowler@elliptictech.com>
>>
>> -------------------
>> This is a commit scheduled for the next v2.6.34 longterm release.
>> http://git.kernel.org/?p=linux/kernel/git/paulg/longterm-queue-2.6.34.git
>> If you see a problem with using this for longterm, please comment.
>> -------------------
>>
>> commit 7ed47b7d142ec99ad6880bbbec51e9f12b3af74c upstream.
>>
>> The ghash_update function passes a pointer to gf128mul_4k_lle which will
>> be NULL if ghash_setkey is not called or if the most recent call to
>> ghash_setkey failed to allocate memory. This causes an oops. Fix this
>> up by returning an error code in the null case.
>>
>> This is trivially triggered from unprivileged userspace through the
>> AF_ALG interface by simply writing to the socket without setting a key.
>
> I haven't been following 2.6.34-longterm development, but unless
> you've also backported the AF_ALG userspace interface from 2.6.38,
> this sequence can only be triggered by kernel code. So while this
> patch shouldn't break anything, it isn't really necessary.

We've not backported any features or interfaces, as doing so is
generally outside of the mandate of what -stable tries to achieve.
So I'll simply drop the patch.

Thanks for the info.
Paul
--

>
> Cheers,
>