On Thu, Mar 03, 2022 at 09:43:28AM -0800, Kees Cook wrote:
> On Thu, Mar 03, 2022 at 11:25:03AM -0600, Gustavo A. R. Silva wrote:
> > Fix the following Wstringop-overflow warnings when building with GCC-11:
> >
> > drivers/gpu/drm/amd/amdgpu/../display/dc/core/dc_link_dpia.c:493:17: warning: ‘dp_decide_lane_settings’ accessing 4 bytes in a region of size 1 [-Wstringop-overflow=]
>
> Can you "show your work" a little more here? I don't actually see the
> what is getting fixed:
>
> enum dc_lane_count {
> ...
> LANE_COUNT_FOUR = 4,
> ...
> LANE_COUNT_DP_MAX = LANE_COUNT_FOUR
> };
>
> struct link_training_settings {
> ...
> union dpcd_training_lane dpcd_lane_settings[LANE_COUNT_DP_MAX];
> };
>
> void dp_hw_to_dpcd_lane_settings(
> ...
> union dpcd_training_lane dpcd_lane_settings[LANE_COUNT_DP_MAX])
> {
> ...
> }
>
> static enum link_training_result dpia_training_cr_transparent(
> ...
> struct link_training_settings *lt_settings)
> {
> ...
> dp_decide_lane_settings(lt_settings, dpcd_lane_adjust,
> lt_settings->hw_lane_settings, lt_settings->dpcd_lane_settings);
> ...
> }
>
> Everything looks to be the correct size?
Yep; this fix is similar to the one for intel_pm.c in this
commit e7c6e405e171fb33990a12ecfd14e6500d9e5cf2
where the array size of 8 seems to be fine for all the
struct members related (pri_latency, spr_latency, cur_latency
and skl_latency):
drivers/gpu/drm/i915/i915_drv.h:465:struct drm_i915_private {
...
drivers/gpu/drm/i915/i915_drv.h-739- struct {
...
drivers/gpu/drm/i915/i915_drv.h-745- /* primary */
drivers/gpu/drm/i915/i915_drv.h-746- u16 pri_latency[5];
drivers/gpu/drm/i915/i915_drv.h-747- /* sprite */
drivers/gpu/drm/i915/i915_drv.h-748- u16 spr_latency[5];
drivers/gpu/drm/i915/i915_drv.h-749- /* cursor */
drivers/gpu/drm/i915/i915_drv.h-750- u16 cur_latency[5];
drivers/gpu/drm/i915/i915_drv.h-751- /*
drivers/gpu/drm/i915/i915_drv.h-752- * Raw watermark memory latency values
drivers/gpu/drm/i915/i915_drv.h-753- * for SKL for all 8 levels
drivers/gpu/drm/i915/i915_drv.h-754- * in 1us units.
drivers/gpu/drm/i915/i915_drv.h-755- */
drivers/gpu/drm/i915/i915_drv.h-756- u16 skl_latency[8];
...
drivers/gpu/drm/i915/i915_drv.h-773- } wm;
...
}
however GCC warns about accessing bytes beyond the limits, and turning the
argument declarations into pointers (removing the over-specified array
size from the argument declaration) silence the warnings.
--
Gustavo
