linux-kernel - [PATCH] drm/amd/display: Check link_index before accessing dc->links[]

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Message-Id: <20250123120822.1983325-1-spushpka@cisco.com>
Date: Thu, 23 Jan 2025 04:08:22 -0800
From: Shubham Pushpkar <spushpka@...co.com>
To: stable@...r.kernel.org
Cc: linux-kernel@...r.kernel.org,
	deeratho@...co.com,
	Harry Wentland <harry.wentland@....com>,
	Tom Chung <chiahsuan.chung@....com>,
	Daniel Wheeler <daniel.wheeler@....com>,
	Shubham Pushpkar <spushpka@...co.com>
Subject: [PATCH] drm/amd/display: Check link_index before accessing dc->links[]

From: Alex Hung <alex.hung@....com>

commit 8aa2864044b9d13e95fe224f32e808afbf79ecdf ("drm/amd/display:
Check link_index before accessing dc->links[]")

[WHY & HOW]
dc->links[] has max size of MAX_LINKS and NULL is return when trying to
access with out-of-bound index.

This fixes 3 OVERRUN and 1 RESOURCE_LEAK issues reported by Coverity.

Fixes: CVE-2024-46813
Reviewed-by: Harry Wentland <harry.wentland@....com>
Acked-by: Tom Chung <chiahsuan.chung@....com>
Signed-off-by: Alex Hung <alex.hung@....com>
Tested-by: Daniel Wheeler <daniel.wheeler@....com>
Signed-off-by: Alex Deucher <alexander.deucher@....com>
(cherry picked from commit 8aa2864044b9d13e95fe224f32e808afbf79ecdf)
Signed-off-by: Shubham Pushpkar <spushpka@...co.com>
---
 drivers/gpu/drm/amd/display/dc/core/dc_link_exports.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/amd/display/dc/core/dc_link_exports.c b/drivers/gpu/drm/amd/display/dc/core/dc_link_exports.c
index f365773d5714..b5639e88c581 100644
--- a/drivers/gpu/drm/amd/display/dc/core/dc_link_exports.c
+++ b/drivers/gpu/drm/amd/display/dc/core/dc_link_exports.c
@@ -37,6 +37,9 @@
 #include "dce/dce_i2c.h"
 struct dc_link *dc_get_link_at_index(struct dc *dc, uint32_t link_index)
 {
+	if (link_index >= MAX_LINKS)
+		return NULL;
+
 	return dc->links[link_index];
 }
 
-- 
2.35.6