Re: [PATCH v8 0/9] crypto: Remove VLA usage

[Kees Cook]

On Mon, Sep 3, 2018 at 10:19 PM, Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx> wrote:
> On Tue, Aug 07, 2018 at 02:18:34PM -0700, Kees Cook wrote:
>> v8 cover letter:
>>
>> I continue to hope this can land in v4.19, but I realize that's unlikely.
>> It would be nice, though, if some of the "trivial" patches could get taken
>> (e.g. cbc, xcbc, ccm VLA removals) so I don't have to keep repeating them.
>> *fingers crossed*
>>
>> Series cover letter:
>>
>> This is nearly the last of the VLA removals[1], but it's one of the
>> largest because crypto gets used in lots of places. After looking
>> through code, usage, reading the threads Gustavo started, and comparing
>> the use-cases to the other VLA removals that have landed in the kernel,
>> I think this series is likely the best way forward to shut the door on
>> VLAs forever.
>>
>> For background, the crypto stack usage is for callers to do an immediate
>> bit of work that doesn't allocate new memory. This means that other VLA
>> removal techniques (like just using kmalloc) aren't workable, and the
>> next common technique is needed: examination of maximum stack usage and
>> the addition of sanity checks. This series does that, and in several
>> cases, these maximums were already implicit in the code.
>>
>> This series is intended to land via the crypto tree for 4.19, though it
>> touches dm, networking, and a few other things as well, since there are
>> dependent patches (new crypto #defines being used, etc).
>
> I have applied patches 1-4 and 6-8.  I'd like to get an ack from
> the dm folks regarding patch 5.  As to patch 9, please fix it so
> it doesn't rely on the BUG_ON to catch things.

Great! Thanks very much. I'll get a patch prepared to plumb
crypto_skcipher_set_reqsize() failures.

-Kees

-- 
Kees Cook
Pixel Security