linux-kernel - Re: [PATCH v2] drm/nouveau/secboot: remove VLA usage

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Date:   Thu, 24 May 2018 10:36:58 +1000
From:   Ben Skeggs <bskeggs@...hat.com>
To:     Kees Cook <keescook@...omium.org>
Cc:     Ben Skeggs <skeggsb@...il.com>,
        Daniel Vetter <daniel.vetter@...ll.ch>,
        Thierry Reding <thierry.reding@...il.com>,
        "Gustavo A. R. Silva" <gustavo@...eddedor.com>,
        David Airlie <airlied@...ux.ie>,
        nouveau <nouveau@...ts.freedesktop.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Maling list - DRI developers 
        <dri-devel@...ts.freedesktop.org>,
        David Laight <David.Laight@...lab.com>
Subject: Re: [PATCH v2] drm/nouveau/secboot: remove VLA usage

On Thu, May 24, 2018 at 8:48 AM, Kees Cook <keescook@...omium.org> wrote:
> On Thu, Apr 26, 2018 at 4:25 PM, Kees Cook <keescook@...omium.org> wrote:
>> On Thu, Mar 15, 2018 at 7:05 PM, Ben Skeggs <skeggsb@...il.com> wrote:
>>> On 14 March 2018 at 21:08, Thierry Reding <thierry.reding@...il.com> wrote:
>>>> On Tue, Mar 13, 2018 at 11:24:11AM -0500, Gustavo A. R. Silva wrote:
>>>>> In preparation to enabling -Wvla, remove VLA. In this particular
>>>>> case directly use macro NVKM_MSGQUEUE_CMDLINE_SIZE instead of local
>>>>> variable cmdline_size. Also, remove cmdline_size as it is not
>>>>> actually useful anymore.
>>>>>
>>>>> The use of stack Variable Length Arrays needs to be avoided, as they
>>>>> can be a vector for stack exhaustion, which can be both a runtime bug
>>>>> or a security flaw. Also, in general, as code evolves it is easy to
>>>>> lose track of how big a VLA can get. Thus, we can end up having runtime
>>>>> failures that are hard to debug.
>>>>>
>>>>> Also, fixed as part of the directive to remove all VLAs from
>>>>> the kernel: https://lkml.org/lkml/2018/3/7/621
>>>>>
>>>>> Signed-off-by: Gustavo A. R. Silva <gustavo@...eddedor.com>
>>>>> ---
>>>>> Changes in v2:
>>>>>  - Use sizeof(buf) instead of NVKM_MSGQUEUE_CMDLINE_SIZE. This change
>>>>>    is based on the feedback provided by David Laight. Thanks David.
>>>>>
>>>>>  drivers/gpu/drm/nouveau/nvkm/subdev/secboot/ls_ucode_msgqueue.c | 7 +++----
>>>>>  1 file changed, 3 insertions(+), 4 deletions(-)
>>>>
>>>> Reviewed-by: Thierry Reding <treding@...dia.com>
>>> Thanks everyone.  I've taken the patch in my tree.
>>
>> Hi!
>>
>> Just checking in on this -- I don't see this patch in linux-next. Is
>> this queued somewhere else?
>
> Hi, it's been another month; I still don't see this in linux-next.
> Daniel, can this go via drm-misc?
It's already queued in drm-next.

>
> -Kees
>
> --
> Kees Cook
> Pixel Security