[PATCH 2/2] drm/mst: Add range check for max_payloads during init

[Imre Deak]

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 at intel.com>
---
 drivers/gpu/drm/drm_dp_mst_topology.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c
index 8f749e6..05c2702 100644
--- a/drivers/gpu/drm/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/drm_dp_mst_topology.c
@@ -2847,6 +2847,9 @@ 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;
-- 
2.5.0