drm/mst: Add range check for max_payloads during init

max_payload is limited by the space we have in
drm_dp_mst_topology_mgr::vcpi_mask,payload_mask. We need to track
max_payloads+1 IDs in these masks, see drm_dp_mst_assign_payload_id().
Add a sanity check for this.

Caught by coverity.

Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: David Weinehall <david.weinehall@intel.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

1 files changed, 3 insertions, 0 deletions

diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c
index 2b7c2f068834..0680e7aecac4 100644
--- a/drivers/gpu/drm/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/drm_dp_mst_topology.c
@@ -2848,6 +2848,9 @@ int drm_dp_mst_topology_mgr_init(struct drm_dp_mst_topology_mgr *mgr,
         mgr->max_dpcd_transaction_bytes = max_dpcd_transaction_bytes;
         mgr->max_payloads = max_payloads;
         mgr->conn_base_id = conn_base_id;
+        if (max_payloads + 1 > sizeof(mgr->payload_mask) * 8 ||
+            max_payloads + 1 > sizeof(mgr->vcpi_mask) * 8)
+                return -EINVAL;
         mgr->payloads = kcalloc(max_payloads, sizeof(struct drm_dp_payload), GFP_KERNEL);
         if (!mgr->payloads)
                 return -ENOMEM;