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

From: Kees Cook
Date: Thu Apr 26 2018 - 19:26:03 EST

On Thu, Mar 15, 2018 at 7:05 PM, Ben Skeggs <skeggsb@xxxxxxxxx> wrote:
> On 14 March 2018 at 21:08, Thierry Reding <thierry.reding@xxxxxxxxx> 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:
>>> Signed-off-by: Gustavo A. R. Silva <gustavo@xxxxxxxxxxxxxx>
>>> ---
>>> 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@xxxxxxxxxx>
> Thanks everyone. I've taken the patch in my tree.


Just checking in on this -- I don't see this patch in linux-next. Is
this queued somewhere else?



Kees Cook
Pixel Security