linux-kernel - [PATCH] drm/mst: Fix NULL pointer dereference in drm_dp_add_payload

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Message-ID: <20240413002252.30780-1-jeffm@suse.com>
Date: Fri, 12 Apr 2024 20:22:52 -0400
From: Jeff Mahoney <jeffm@...e.com>
To: Wayne Lin <Wayne.Lin@....com>,
	dri-devel@...ts.freedesktop.org
Cc: linux-kernel@...r.kernel.org,
	David Airlie <airlied@...il.com>,
	Daniel Vetter <daniel@...ll.ch>,
	Jeff Mahoney <jeffm@...e.com>,
	stable@...r.kernel.org
Subject: [PATCH] drm/mst: Fix NULL pointer dereference in drm_dp_add_payload_part2 (again)

Commit 54d217406afe (drm: use mgr->dev in drm_dbg_kms in
drm_dp_add_payload_part2) appears to have been accidentially reverted as
part of commit 5aa1dfcdf0a42 (drm/mst: Refactor the flow for payload
allocation/removement).

I've been seeing NULL pointer dereferences in drm_dp_add_payload_part2
due to state->dev being NULL in the debug message printed if the payload
allocation has failed.

This commit restores mgr->dev to avoid the Oops.

Fixes: 5aa1dfcdf0a42 ("drm/mst: Refactor the flow for payload allocation/removement")
Cc: stable@...r.kernel.org
Signed-off-by: Jeff Mahoney <jeffm@...e.com>
---
 drivers/gpu/drm/display/drm_dp_mst_topology.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/display/drm_dp_mst_topology.c b/drivers/gpu/drm/display/drm_dp_mst_topology.c
index 03d528209426..3dc966f25c0c 100644
--- a/drivers/gpu/drm/display/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/display/drm_dp_mst_topology.c
@@ -3437,7 +3437,7 @@ int drm_dp_add_payload_part2(struct drm_dp_mst_topology_mgr *mgr,
 
 	/* Skip failed payloads */
 	if (payload->payload_allocation_status != DRM_DP_MST_PAYLOAD_ALLOCATION_DFP) {
-		drm_dbg_kms(state->dev, "Part 1 of payload creation for %s failed, skipping part 2\n",
+		drm_dbg_kms(mgr->dev, "Part 1 of payload creation for %s failed, skipping part 2\n",
 			    payload->port->connector->name);
 		return -EIO;
 	}
-- 
2.44.0