linux-kernel - Re: [PATCH v2] crypto/ecc: Remove stack VLA usage

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Message-ID: <CAGXu5jKJ-05xb8x7A4dZmFQm10z5g9x1LhFbC1nzLT7kdVVbGg@mail.gmail.com>
Date:   Mon, 26 Mar 2018 15:38:59 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Herbert Xu <herbert@...dor.apana.org.au>
Cc:     Tudor Ambarus <tudor.ambarus@...rochip.com>,
        "David S. Miller" <davem@...emloft.net>,
        linux-crypto <linux-crypto@...r.kernel.org>,
        Kernel Hardening <kernel-hardening@...ts.openwall.com>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] crypto/ecc: Remove stack VLA usage

On Fri, Mar 16, 2018 at 8:56 AM, Herbert Xu <herbert@...dor.apana.org.au> wrote:
> On Thu, Mar 08, 2018 at 01:57:02PM -0800, Kees Cook wrote:
>> On the quest to remove all VLAs from the kernel[1], this switches to
>> a pair of kmalloc regions instead of using the stack. This also moves
>> the get_random_bytes() after all allocations (and drops the needless
>> "nbytes" variable).
>>
>> [1] https://lkml.org/lkml/2018/3/7/621
>>
>> Signed-off-by: Kees Cook <keescook@...omium.org>
>
> Patch applied.  Thanks.

Hi, sorry for the noise on this one: I messed up looking at the ecc
code (I confused myself into thinking there was only a single instance
of the problem). The applied patch is both incomplete and inefficient.
I have a much simpler solution, and I'll send that with a revert...

-Kees

-- 
Kees Cook
Pixel Security