From d6b8bbca6bc83b9c57e528b28df6177b9b57e19d Mon Sep 17 00:00:00 2001 From: Benjamin Gaignard Date: Mon, 3 Feb 2020 13:16:20 +0100 Subject: [PATCH] drm/dp_mst: Check crc4 value while building sideband message Check that computed crc value is matching the one encoded in the message. Signed-off-by: Benjamin Gaignard Reviewed-by: Lyude Paul Link: https://patchwork.freedesktop.org/patch/msgid/20200203121620.9002-1-benjamin.gaignard@st.com --- drivers/gpu/drm/drm_dp_mst_topology.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c index ba15a15bce9e..61e7beada832 100644 --- a/drivers/gpu/drm/drm_dp_mst_topology.c +++ b/drivers/gpu/drm/drm_dp_mst_topology.c @@ -736,6 +736,10 @@ static bool drm_dp_sideband_msg_build(struct drm_dp_sideband_msg_rx *msg, if (msg->curchunk_idx >= msg->curchunk_len) { /* do CRC */ crc4 = drm_dp_msg_data_crc4(msg->chunk, msg->curchunk_len - 1); + if (crc4 != msg->chunk[msg->curchunk_len - 1]) + print_hex_dump(KERN_DEBUG, "wrong crc", + DUMP_PREFIX_NONE, 16, 1, + msg->chunk, msg->curchunk_len, false); /* copy chunk into bigger msg */ memcpy(&msg->msg[msg->curlen], msg->chunk, msg->curchunk_len - 1); msg->curlen += msg->curchunk_len - 1;