linux-kernel - [WIP PATCH 14/15] drm/dp_mst: Check payload count in drm_dp_mst_atomic

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Date:   Thu, 13 Dec 2018 20:25:43 -0500
From:   Lyude Paul <lyude@...hat.com>
To:     dri-devel@...ts.freedesktop.org, nouveau@...ts.freedesktop.org,
        intel-gfx@...ts.freedesktop.org, amd-gfx@...ts.freedesktop.org
Cc:     Daniel Vetter <daniel@...ll.ch>, Dave Airlie <airlied@...il.com>,
        Harry Wentland <harry.wentland@....com>,
        Jerry Zuo <Jerry.Zuo@....com>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Maxime Ripard <maxime.ripard@...tlin.com>,
        Sean Paul <sean@...rly.run>, David Airlie <airlied@...ux.ie>,
        linux-kernel@...r.kernel.org
Subject: [WIP PATCH 14/15] drm/dp_mst: Check payload count in drm_dp_mst_atomic_check()

It occurred to me that we never actually check this! So let's start
doing that.

Signed-off-by: Lyude Paul <lyude@...hat.com>
Reviewed-by: Daniel Vetter <daniel.vetter@...ll.ch>
---
 drivers/gpu/drm/drm_dp_mst_topology.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c
index b9374c981a5b..ebffb834f5d6 100644
--- a/drivers/gpu/drm/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/drm_dp_mst_topology.c
@@ -3538,7 +3538,7 @@ drm_dp_mst_atomic_check_topology_state(struct drm_dp_mst_topology_mgr *mgr,
 				       struct drm_dp_mst_topology_state *mst_state)
 {
 	struct drm_dp_vcpi_allocation *vcpi;
-	int avail_slots = 63, ret;
+	int avail_slots = 63, payload_count = 0, ret;
 
 	/* There's no possible scenario where releasing VCPI or keeping it the
 	 * same would make the state invalid
@@ -3575,6 +3575,13 @@ drm_dp_mst_atomic_check_topology_state(struct drm_dp_mst_topology_mgr *mgr,
 			goto port_fail;
 		}
 
+		if (++payload_count > mgr->max_payloads) {
+			DRM_DEBUG_ATOMIC("[MST MGR:%p] state %p has too many payloads (max=%d)\n",
+					 mgr, mst_state, mgr->max_payloads);
+			ret = -EINVAL;
+			goto port_fail;
+		}
+
 		drm_dp_mst_topology_put_port(vcpi->port);
 	}
 	DRM_DEBUG_ATOMIC("[MST MGR:%p] mst state %p VCPI avail=%d used=%d\n",
-- 
2.19.2