linux-kernel - [lvc-project] [PATCH] drm/radeon: fix possible NULL pointer dereference in atombios_set_encoder_crtc

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Message-Id: <20250423123142.1499351-1-Igor.A.Artemiev@mcst.ru>
Date: Wed, 23 Apr 2025 15:31:42 +0300
From: Igor Artemiev <Igor.A.Artemiev@...t.ru>
To: Alex Deucher <alexander.deucher@....com>
Cc: Igor Artemiev <Igor.A.Artemiev@...t.ru>,
	Christian König <christian.koenig@....com>,
	David Airlie <airlied@...il.com>,
	Simona Vetter <simona@...ll.ch>,
	amd-gfx@...ts.freedesktop.org,
	dri-devel@...ts.freedesktop.org,
	linux-kernel@...r.kernel.org,
	lvc-project@...uxtesting.org
Subject: [lvc-project] [PATCH] drm/radeon: fix possible NULL pointer dereference in atombios_set_encoder_crtc_source()

The function radeon_get_connector_for_encoder() can return NULL
and its result is checked before dereference in all functions
except atombios_set_encoder_crtc_source().

Add a NULL pointer check before dereference.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Fixes: a4863ca93ccc ("drm/radeon/kms/DCE4.1: fix Select_CrtcSource EncodeMode setting for DP bridges (v2)")
Signed-off-by: Igor Artemiev <Igor.A.Artemiev@...t.ru>
---
 drivers/gpu/drm/radeon/atombios_encoders.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/radeon/atombios_encoders.c b/drivers/gpu/drm/radeon/atombios_encoders.c
index d1c5e471bdca..0cda4e6749f0 100644
--- a/drivers/gpu/drm/radeon/atombios_encoders.c
+++ b/drivers/gpu/drm/radeon/atombios_encoders.c
@@ -1913,9 +1913,9 @@ atombios_set_encoder_crtc_source(struct drm_encoder *encoder)
 			if (radeon_encoder_get_dp_bridge_encoder_id(encoder) != ENCODER_OBJECT_ID_NONE) {
 				struct drm_connector *connector = radeon_get_connector_for_encoder(encoder);
 
-				if (connector->connector_type == DRM_MODE_CONNECTOR_LVDS)
+				if (connector && connector->connector_type == DRM_MODE_CONNECTOR_LVDS)
 					args.v2.ucEncodeMode = ATOM_ENCODER_MODE_LVDS;
-				else if (connector->connector_type == DRM_MODE_CONNECTOR_VGA)
+				else if (connector && connector->connector_type == DRM_MODE_CONNECTOR_VGA)
 					args.v2.ucEncodeMode = ATOM_ENCODER_MODE_CRT;
 				else
 					args.v2.ucEncodeMode = atombios_get_encoder_mode(encoder);
-- 
2.39.2