[PATCH 4.4 29/29] drm_dp_mst_topology: fix broken drm_dp_sideband_parse_remote_dpcd_read()

From: Greg Kroah-Hartman
Date: Sat Apr 11 2020 - 08:11:28 EST


From: Hans Verkuil <hans.verkuil@xxxxxxxxx>

commit a4c30a4861c54af78c4eb8b7855524c1a96d9f80 upstream.

When parsing the reply of a DP_REMOTE_DPCD_READ DPCD command the
result is wrong due to a missing idx increment.

This was never noticed since DP_REMOTE_DPCD_READ is currently not
used, but if you enable it, then it is all wrong.

Signed-off-by: Hans Verkuil <hans.verkuil@xxxxxxxxx>
Reviewed-by: Lyude Paul <lyude@xxxxxxxxxx>
Acked-by: Alex Deucher <alexander.deucher@xxxxxxx>
Link: https://patchwork.freedesktop.org/patch/msgid/e72ddac2-1dc0-100a-d816-9ac98ac009dd@xxxxxxxxx
Signed-off-by: Lee Jones <lee.jones@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
drivers/gpu/drm/drm_dp_mst_topology.c | 1 +
1 file changed, 1 insertion(+)

--- a/drivers/gpu/drm/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/drm_dp_mst_topology.c
@@ -431,6 +431,7 @@ static bool drm_dp_sideband_parse_remote
if (idx > raw->curlen)
goto fail_len;
repmsg->u.remote_dpcd_read_ack.num_bytes = raw->msg[idx];
+ idx++;
if (idx > raw->curlen)
goto fail_len;