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