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

Message ID ZBSu2QsUJy31kjSE@work
State New
Headers
Series [next] drm/i915/uapi: Replace fake flex-array with flexible-array member |

Commit Message

Gustavo A. R. Silva March 17, 2023, 6:18 p.m. UTC 
  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(-)

Comments

Kees Cook March 20, 2023, 5:36 p.m. UTC | #1 
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>
Tvrtko Ursulin March 21, 2023, 8:43 a.m. UTC | #2 
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
Gustavo A. R. Silva March 30, 2023, 8:13 p.m. UTC | #3 
Hi all,

Friendly ping: who can take this, please? 😄

Thanks
Jani Nikula March 31, 2023, 7:02 a.m. UTC | #4 
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
Gustavo A. R. Silva April 6, 2023, 4:27 p.m. UTC | #5 
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
> 
>
diff mbox series

Patch

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 { \