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drm/mst: Fix possible NULL pointer dereference in drm_dp_mst_process_up_req() 

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: 9408cc94eb ("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.souza@intel.com
This commit is contained in:
José Roberto de Souza 2020-01-29 15:24:48 -08:00 committed by Lyude Paul
parent cf913e9683
commit 8ccb5bf761
1 changed files with 2 additions and 1 deletions
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3
drivers/gpu/drm/drm_dp_mst_topology.c
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@ -3760,7 +3760,8 @@ 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);
}