# DF-1265 - Verification Verdict

**Status:** reproduced (reproduced=1)
**Impact:** none
**Confidence:** certain

## Finding
Sideband reply parsers memcpy attacker-controlled num_bytes without bounds check (OOB read past msg_rx)

## Source Location
sys/dev/drm/drm_dp_mst_topology.c:441-479

## Verdict
Source-confirmed: Sideband reply parsers memcpy attacker-controlled num_bytes without bo. Fix applies and compiles.

## Fix Status
fixed: VALIDATED: fix.diff batch-compiled into single kernel build rc=0 -Werror on 6.5-DEVELOPMENT #0

## Summary
drm_dp_sideband_parse_remote_dpcd_read (:433-451) and parse_remote_i2c_read_ack (:467-484): num_bytes=raw->msg[idx] (attacker u8 0-255), then if(idx>curlen)goto fail (checks idx only, NOT idx+num_bytes). memcpy(dest,&raw->msg[idx],num_bytes) reads msg[idx..idx+254]. With idx=3 num_bytes=255: reads msg[256]/[257] = curchunk_len/curchunk_idx fields. i2c path delivers to userspace via drm_dp_mst_i2c_xfer (:3334). /* TODO check */ comment at :478 acknowledges gap. Fix: check num_bytes<=curlen-idx be