diff --git a/drivers/gpu/drm/display/drm_dp_mst_topology.c b/drivers/gpu/drm/display/drm_dp_mst_topology.c
index 35dc4f24ae53..fe72245fb9ca 100644
--- a/drivers/gpu/drm/display/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/display/drm_dp_mst_topology.c
@@ -789,6 +789,12 @@ static bool drm_dp_sideband_append_payload(struct drm_dp_sideband_msg_rx *msg,
 {
 	u8 crc4;
 
+	/* curchunk_len must be >= 1 (min 1 CRC byte) and fit in chunk[] */
+	if (!msg->curchunk_len ||
+	    msg->curchunk_len > ARRAY_SIZE(msg->chunk) ||
+	    msg->curchunk_idx + replybuflen > ARRAY_SIZE(msg->chunk))
+		return false;
+
 	memcpy(&msg->chunk[msg->curchunk_idx], replybuf, replybuflen);
 	msg->curchunk_idx += replybuflen;
 
@@ -799,6 +805,9 @@ static bool drm_dp_sideband_append_payload(struct drm_dp_sideband_msg_rx *msg,
 			print_hex_dump(KERN_DEBUG, "wrong crc",
 				       DUMP_PREFIX_NONE, 16, 1,
 				       msg->chunk,  msg->curchunk_len, false);
+		/* Guard against accumulated msg[] overflow */
+		if (msg->curlen + msg->curchunk_len - 1 > ARRAY_SIZE(msg->msg))
+			return false;
 		/* copy chunk into bigger msg */
 		memcpy(&msg->msg[msg->curlen], msg->chunk, msg->curchunk_len - 1);
 		msg->curlen += msg->curchunk_len - 1;