Re: [PATCH][next] drm/i915/uapi: Replace fake flex-array with flexible-array member

[Tvrtko Ursulin]

On 20/03/2023 17:36, Kees Cook wrote:
> On Fri, Mar 17, 2023 at 12:18:01PM -0600, Gustavo A. R. Silva wrote:
> > Zero-length arrays as fake flexible arrays are deprecated and we are
> > moving towards adopting C99 flexible-array members instead.
> >
> > Address the following warning found with GCC-13 and
> > -fstrict-flex-arrays=3 enabled:
> > drivers/gpu/drm/i915/gem/i915_gem_context.c: In function ‘set_proto_ctx_engines.isra’:
> > drivers/gpu/drm/i915/gem/i915_gem_context.c:769:41: warning: array subscript n is outside array bounds of ‘struct i915_engine_class_instance[0]’ [-Warray-bounds=]
> >    769 |                 if (copy_from_user(&ci, &user->engines[n], sizeof(ci))) {
> >        |                                         ^~~~~~~~~~~~~~~~~
> > ./include/uapi/drm/i915_drm.h:2494:43: note: while referencing ‘engines’
> >   2494 |         struct i915_engine_class_instance engines[0];
> >
> > This helps with the ongoing efforts to tighten the FORTIFY_SOURCE
> > routines on memcpy() and help us make progress towards globally
> > enabling -fstrict-flex-arrays=3 [1].
> >
> > Link: https://github.com/KSPP/linux/issues/21
> > Link: https://github.com/KSPP/linux/issues/271
> > Link: https://gcc.gnu.org/pipermail/gcc-patches/2022-October/602902.html [1]
> > Signed-off-by: Gustavo A. R. Silva <gustavoars@xxxxxxxxxx>
>
> Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx>

Flexible array member is even consistent with the rest of our uapi, 
pushed to drm-intel-gt-next, thanks!

Regards,

Tvrtko