Re: [v2.6.34-stable 004/213] crypto: ghash - Avoid null pointer dereference if no key is set

[Paul Gortmaker <paul.gortmaker@windriver.com>]

On 14-02-05 03:30 PM, Nick Bowler wrote:
> On 2014-02-05 14:59 -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.
> 
> After all this time, I see this patch still manages to find its way,
> occasionally, into the patch queue for older -stable. :)
> 
> It should be harmless to apply, but this patch doesn't actually fix
> any real problem on kernels previous to 2.6.38 because the AF_ALG
> userspace interface does not exist in these kernels.

Thanks, I'll drop it then, since less churn in a stable release is
desired, where possible.  I saw it tagged 2.6.37+, but then I also
saw it applied in 2.6.32.x, so I wasn't sure what to make of it.

Paul.
--

> 
> Cheers,
>