drm/mst: Fix error handling during MST sideband message reception
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@redhat.com>
Cc: Lyude <lyude@redhat.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Lyude <lyude@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20170719114330.26540-2-imre.deak@intel.com
diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c
index bfd237c..ce0e584 100644
--- a/drivers/gpu/drm/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/drm_dp_mst_topology.c
@@ -2196,11 +2196,17 @@ 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;
}