[5.10.y] drm/amd/display: Stop amdgpu_dm initialize when link nums greater than max_links

Commit Message

Ren, Jianqi (Jacky) (CN) April 16, 2025, 1:18 a.m. UTC

From: Hersen Wu <[e-mail]>

[ Upstream commit cf8b16857db702ceb8d52f9219a4613363e2b1cf ]

[Why]
Coverity report OVERRUN warning. There are
only max_links elements within dc->links. link
count could up to AMDGPU_DM_MAX_DISPLAY_INDEX 31.

[How]
Make sure link count less than max_links.

Reviewed-by: Harry Wentland <[e-mail]>
Acked-by: Tom Chung <[e-mail]>
Signed-off-by: Hersen Wu <[e-mail]>
Tested-by: Daniel Wheeler <[e-mail]>
Signed-off-by: Alex Deucher <[e-mail]>
[Minor conflict resolved due to code context change. And the macro MAX_LINKS
 is introduced by Commit 60df5628144b ("drm/amd/display: handle invalid
 connector indices") after 6.10. So here we still use the original array
 length MAX_PIPES * 2]
Signed-off-by: Jianqi Ren <[e-mail]>
Signed-off-by: He Zhe <[e-mail]>
---
Verified the build test
---
 drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

Patch

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
index 50921b340b88..69b3f1dc43e5 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -3397,17 +3397,17 @@  static int amdgpu_dm_initialize_drm_device(struct amdgpu_device *adev)
 			goto fail;
 		}
 
+	if (link_cnt > (MAX_PIPES * 2)) {
+		DRM_ERROR(
+			"KMS: Cannot support more than %d display indexes\n",
+				MAX_PIPES * 2);
+		goto fail;
+	}
+
 	/* loops over all connectors on the board */
 	for (i = 0; i < link_cnt; i++) {
 		struct dc_link *link = NULL;
 
-		if (i > AMDGPU_DM_MAX_DISPLAY_INDEX) {
-			DRM_ERROR(
-				"KMS: Cannot support more than %d display indexes\n",
-					AMDGPU_DM_MAX_DISPLAY_INDEX);
-			continue;
-		}
-
 		aconnector = kzalloc(sizeof(*aconnector), GFP_KERNEL);
 		if (!aconnector)
 			goto fail;