[PATCH] drm/amdgpu/dm: Fix NULL pointer crash during DP MST hotplug

[Shashank Sharma]

This patch checks the return value of the function
dc_link_add_remote_sink before using it. This was causing
a crash during consecutive hotplugs of DP MST displays.

Cc: Harry Wentland <harry.wentland at amd.com>
Signed-off-by: Shashank Sharma <shashank.sharma at amd.com>
---
 drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c
index eee19edeeee5..8dc5005bec0a 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c
@@ -226,6 +226,11 @@ static int dm_dp_mst_get_modes(struct drm_connector *connector)
 			(aconnector->edid->extensions + 1) * EDID_LENGTH,
 			&init_params);
 
+		if (!dc_sink) {
+			DRM_ERROR("Unable to add a remote sink\n");
+			return 0;
+		}
+
 		dc_sink->priv = aconnector;
 		/* dc_link_add_remote_sink returns a new reference */
 		aconnector->dc_sink = dc_sink;
-- 
2.25.1