linux-kernel - [PATCH 6.6.y] drm/amd/display: Stop amdgpu_dm initialize when link nums greater than max

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Message-ID: <20250416011721.388632-1-jianqi.ren.cn@windriver.com>
Date: Wed, 16 Apr 2025 09:17:21 +0800
From: <jianqi.ren.cn@...driver.com>
To: <gregkh@...uxfoundation.org>, <stable@...r.kernel.org>
CC: <patches@...ts.linux.dev>, <linux-kernel@...r.kernel.org>,
        <jianqi.ren.cn@...driver.com>, <harry.wentland@....com>,
        <sunpeng.li@....com>, <Rodrigo.Siqueira@....com>,
        <alexander.deucher@....com>, <christian.koenig@....com>,
        <Xinhui.Pan@....com>, <airlied@...il.com>, <daniel@...ll.ch>,
        <sashal@...nel.org>, <chiahsuan.chung@....com>, <alex.hung@....com>,
        <mario.limonciello@....com>, <hersenxs.wu@....com>,
        <Wayne.Lin@....com>, <amd-gfx@...ts.freedesktop.org>,
        <dri-devel@...ts.freedesktop.org>, <daniel.wheeler@....com>
Subject: [PATCH 6.6.y] drm/amd/display: Stop amdgpu_dm initialize when link nums greater than max_links

From: Hersen Wu <hersenxs.wu@....com>

[ 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 <harry.wentland@....com>
Acked-by: Tom Chung <chiahsuan.chung@....com>
Signed-off-by: Hersen Wu <hersenxs.wu@....com>
Tested-by: Daniel Wheeler <daniel.wheeler@....com>
Signed-off-by: Alex Deucher <alexander.deucher@....com>
[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 <jianqi.ren.cn@...driver.com>
Signed-off-by: He Zhe <zhe.he@...driver.com>
---
Verified the build test
---
 drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

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 3696b9112c74..28f2b4022d34 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -4484,17 +4484,17 @@ static int amdgpu_dm_initialize_drm_device(struct amdgpu_device *adev)
 		}
 	}
 
+	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;
-- 
2.34.1