[PATCH 2/3] drm/mst: Fix error handling during MST sideband message reception

[Imre Deak]

Handle any error due to partial reads, timeouts etc. to avoid parsing
uninitialized data subsequently. Also bail out if the parsing itself
fails.

CC: Dave Airlie <airlied at redhat.com>
Signed-off-by: Imre Deak <imre.deak at intel.com>
---
 drivers/gpu/drm/drm_dp_mst_topology.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c
index a13edf5..12c0ab3 100644
--- a/drivers/gpu/drm/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/drm_dp_mst_topology.c
@@ -2204,11 +2204,19 @@ static void drm_dp_get_one_sb_msg(struct drm_dp_mst_topology_mgr *mgr, bool up)
 		ret = drm_dp_dpcd_read(mgr->aux, basereg + curreply,
 				    replyblock, len);
 		if (ret != len) {
-			DRM_DEBUG_KMS("failed to read a chunk\n");
+			DRM_DEBUG_KMS("failed to read a chunk (len %d, ret %d)\n",
+				      len, ret);
+
+			return;
 		}
+
 		ret = drm_dp_sideband_msg_build(msg, replyblock, len, false);
-		if (ret == false)
+		if (!ret) {
 			DRM_DEBUG_KMS("failed to build sideband msg\n");
+
+			return;
+		}
+
 		curreply += len;
 		replylen -= len;
 	}
-- 
2.5.0