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

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

[Gustavo A. R. Silva]

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>
---
 include/uapi/drm/i915_drm.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/uapi/drm/i915_drm.h b/include/uapi/drm/i915_drm.h
index 8df261c5ab9b..5e458d6f2895 100644
--- a/include/uapi/drm/i915_drm.h
+++ b/include/uapi/drm/i915_drm.h
@@ -2491,7 +2491,7 @@ struct i915_context_param_engines {
 #define I915_CONTEXT_ENGINES_EXT_LOAD_BALANCE 0 /* see i915_context_engines_load_balance */
 #define I915_CONTEXT_ENGINES_EXT_BOND 1 /* see i915_context_engines_bond */
 #define I915_CONTEXT_ENGINES_EXT_PARALLEL_SUBMIT 2 /* see i915_context_engines_parallel_submit */
-	struct i915_engine_class_instance engines[0];
+	struct i915_engine_class_instance engines[];
 } __attribute__((packed));
 
 #define I915_DEFINE_CONTEXT_PARAM_ENGINES(name__, N__) struct { \
-- 
2.34.1

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

[Kees Cook]

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>

-- 
Kees Cook

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@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

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

[Gustavo A. R. Silva]

Hi all,

Friendly ping: who can take this, please? 😄

Thanks
-- 
Gustavo

On 3/17/23 12:18, 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>
> ---
>   include/uapi/drm/i915_drm.h | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/include/uapi/drm/i915_drm.h b/include/uapi/drm/i915_drm.h
> index 8df261c5ab9b..5e458d6f2895 100644
> --- a/include/uapi/drm/i915_drm.h
> +++ b/include/uapi/drm/i915_drm.h
> @@ -2491,7 +2491,7 @@ struct i915_context_param_engines {
>   #define I915_CONTEXT_ENGINES_EXT_LOAD_BALANCE 0 /* see i915_context_engines_load_balance */
>   #define I915_CONTEXT_ENGINES_EXT_BOND 1 /* see i915_context_engines_bond */
>   #define I915_CONTEXT_ENGINES_EXT_PARALLEL_SUBMIT 2 /* see i915_context_engines_parallel_submit */
> -	struct i915_engine_class_instance engines[0];
> +	struct i915_engine_class_instance engines[];
>   } __attribute__((packed));
>   
>   #define I915_DEFINE_CONTEXT_PARAM_ENGINES(name__, N__) struct { \

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

[Jani Nikula]

On Thu, 30 Mar 2023, "Gustavo A. R. Silva" <gustavo@embeddedor.com> wrote:
> Friendly ping: who can take this, please? 😄

It's in drm-intel-gt-next.

commit 02abecdeebfcd3848b26b70778dd7f6eb0db65e1
Author:     Gustavo A. R. Silva <gustavoars@kernel.org>
AuthorDate: Fri Mar 17 12:18:01 2023 -0600
Commit:     Tvrtko Ursulin <tvrtko.ursulin@intel.com>
CommitDate: Tue Mar 21 08:41:18 2023 +0000

    drm/i915/uapi: Replace fake flex-array with flexible-array member


-- 
Jani Nikula, Intel Open Source Graphics Center

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

[Gustavo A. R. Silva]

On 3/31/23 01:02, Jani Nikula wrote:
> On Thu, 30 Mar 2023, "Gustavo A. R. Silva" <gustavo@embeddedor.com> wrote:
>> Friendly ping: who can take this, please? 😄
> 
> It's in drm-intel-gt-next.

Awesome. :) Thank you!

--
Gustavo

> 
> commit 02abecdeebfcd3848b26b70778dd7f6eb0db65e1
> Author:     Gustavo A. R. Silva <gustavoars@kernel.org>
> AuthorDate: Fri Mar 17 12:18:01 2023 -0600
> Commit:     Tvrtko Ursulin <tvrtko.ursulin@intel.com>
> CommitDate: Tue Mar 21 08:41:18 2023 +0000
> 
>      drm/i915/uapi: Replace fake flex-array with flexible-array member
> 
>