linux-kernel - [PATCH] drm/amd/display:fix a Null pointer dereference vulnerability

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Message-ID: <tencent_4A53F3018A4E9A1EAECFAD853F6952D67B06@qq.com>
Date: Thu,  3 Jul 2025 11:39:28 +0800
From: jackysliu <1972843537@...com>
To: harry.wentland@....com
Cc: sunpeng.li@....com,
	siqueira@...lia.com,
	alexander.deucher@....com,
	christian.koenig@....com,
	airlied@...il.com,
	simona@...ll.ch,
	alvin.lee2@....com,
	aurabindo.pillai@....com,
	Dillon.Varone@....com,
	Austin.Zheng@....com,
	Sung.Lee@....com,
	mario.limonciello@....com,
	Wayne.Lin@....com,
	ryanseto@....com,
	linux@...blig.org,
	joshua.aberback@....com,
	amd-gfx@...ts.freedesktop.org,
	dri-devel@...ts.freedesktop.org,
	linux-kernel@...r.kernel.org,
	jackysliu <1972843537@...com>,
	jackysliu <Security@...cent.com>
Subject: [PATCH] drm/amd/display:fix a Null pointer dereference vulnerability

A null pointer dereference vulnerability exists in the AMD display driver's
 (DC module) cleanup function dc_destruct().
 When display control context (dc->ctx) construction fails
 (due to memory allocation failure), this pointer remains NULL.
During subsequent error handling when dc_destruct() is called,
there's no NULL check before dereferencing the perf_trace member
 (dc->ctx->perf_trace),
 causing a kernel null pointer dereference crash

Signed-off-by: jackysliu <Security@...cent.com>
---
 drivers/gpu/drm/amd/display/dc/core/dc.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/gpu/drm/amd/display/dc/core/dc.c b/drivers/gpu/drm/amd/display/dc/core/dc.c
index 56d011a1323c..3bda0593f66f 100644
--- a/drivers/gpu/drm/amd/display/dc/core/dc.c
+++ b/drivers/gpu/drm/amd/display/dc/core/dc.c
@@ -934,6 +934,11 @@ static void dc_destruct(struct dc *dc)
 	if (dc->link_srv)
 		link_destroy_link_service(&dc->link_srv);
 
+	if (!dc->ctx) {
+		dm_error("%s: called with NULL ctx\n", __func__);
+		goto skip_ctx_cleanup;
+	}
+
 	if (dc->ctx->gpio_service)
 		dal_gpio_service_destroy(&dc->ctx->gpio_service);
 
@@ -946,6 +951,7 @@ static void dc_destruct(struct dc *dc)
 	kfree(dc->ctx);
 	dc->ctx = NULL;
 
+skip_ctx_cleanup:
 	kfree(dc->bw_vbios);
 	dc->bw_vbios = NULL;
 
-- 
2.43.5