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

Tvrtko Ursulin
2023-03-21T08:44:36Z

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@kernel.org>
>
> Reviewed-by: Kees Cook <keescook@chromium.org>

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

Regards,

Tvrtko