According to DP specification, DP_SINK_EVENT_NOTIFY is also a broadcast message but as this function only handles DP_CONNECTION_STATUS_NOTIFY I will only make the static analyzer that caught this issue happy by not calling drm_dp_get_mst_branch_device_by_guid() with a NULL guid, causing drm_dp_mst_process_up_req() to return in the "if (!mstb)" right bellow.

Fixes: 9408cc94eb04 ("drm/dp_mst: Handle UP requests asynchronously") Cc: Lyude Paul lyude@redhat.com Cc: Sean Paul sean@poorly.run Cc: stable@vger.kernel.org # v5.5+ Signed-off-by: José Roberto de Souza jose.souza@intel.com [added cc to stable] Signed-off-by: Lyude Paul lyude@redhat.com Link: https://patchwork.freedesktop.org/patch/msgid/20200129232448.84704-1-jose.so... (cherry picked from commit 8ccb5bf7619c6523e7a4384a84b72e7be804298c) --- drivers/gpu/drm/drm_dp_mst_topology.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c index cf6cf186e3c6..c9c43371c33c 100644 --- a/drivers/gpu/drm/drm_dp_mst_topology.c +++ b/drivers/gpu/drm/drm_dp_mst_topology.c @@ -3810,7 +3810,8 @@ drm_dp_mst_process_up_req(struct drm_dp_mst_topology_mgr *mgr, else if (msg->req_type == DP_RESOURCE_STATUS_NOTIFY) guid = msg->u.resource_stat.guid;

- mstb = drm_dp_get_mst_branch_device_by_guid(mgr, guid); + if (guid) + mstb = drm_dp_get_mst_branch_device_by_guid(mgr, guid); } else { mstb = drm_dp_get_mst_branch_device(mgr, hdr->lct, hdr->rad); }