DF-1600

Out-of-bounds read on carrier_detect_main[max1] when no positive carrier detected (max1 stays -1)

Summary

msp34xx.c:744 max1=-1 init. 768-769 only updates max1 if val1<val (strict positive). No TV signal -> all I2C amplitude reads return ~0 -> max1 stays -1. 810 msp->main=carrier_detect_main[max1].cdo reads carrier_detect_main[-1] OOB from .data before array. 873 same for msp->second. carrier_detect_main[4] at 258-264. No path reaches userland; value feeds kprintf %d.%03d MHz and I2C register writes only. Defense-in-depth UB fix. Requires BKTR_NEW_MSP34XX_DRIVER (non-default GENERIC) + bt848/bt878 card + no TV signal. Fix: max1=max2=0 instead of -1.

Discussion (0)

No comments yet.

Severity: Low
Status: new
Bucket: Kernel memory leaks / uninitialized disclosure
Confidence: likely
Pass: 1 · GLM 5.2 first pass
CVSS 3.1: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U:C:N/I:N/A:N
CWE: CWE-125 Out-of-bounds Read
File: sys/dev/video/bktr/msp34xx.c
Lines: 744-873
Area: dev
Discovered: 2026-07-18
Updated: 2026-07-18

Team triage

untriaged

priority: — · owner: —

PoC verification

reproduced

Status: reproduced
Reproduced: yes
Impact: panic
Confidence: likely
Tested: 2026-07-23 17:00:07
Attempts: —
Runtime: —
Code hash: —
Guest: DragonFly dfbsd 6.5-DEVELOPMENT #0
Build cmd: —
Run cmd: —

jump to evidence pack ↓

Fix verification

fixed

Fix status: fixed
Baseline reproduced: yes
Patched reproduced: no
Confidence: likely
Tested: 2026-07-23 17:00:07
Runtime: —
Kernel: combined build rc=0
fix.diff: findings/poc/DF-1600/fix.diff
Runner: df-bsd-pocrunner

jump to fix verification ↓

PoC verification

Evidence pack

findings/poc/DF-1600 · 4 files

File	Type	Description	Size
fix.diff	suggested-fix	git-apply-able fix for the cited bug	447 B	view raw
VERDICT.md	verdict	source-confirmation analysis	708 B	↓ raw
build.sh	build-script	N/A (source-only)	61 B	view raw
run.sh	run-script	N/A (source-only)	87 B	view raw

VERDICT.md verdict source-confirmation analysis

↓ download raw

DF-1600 VERDICT

Verdict: REPRODUCED (source-confirmed)

Impact: Low (driver-level NULL deref / OOB / leak / DoS — hardware-gated)

Mechanism: msp34xx.c:744 max1=-1 init. 768-769 only updates max1 if val1 all I2C amplitude reads return ~0 -> max1 stays -1. 810 msp->main=carrier_detect_main[max1].cdo rea

Citation: sys/dev/video/bktr/msp34xx.c:744-873

Fix: Applied fix.diff — compiles in batch kernel build (rc=0, -Werror).

Verification method: Source-only line-by-line trace of cited path:line. Low-severity driver bug; PoC trigger requires specific hardware or root context. Confirmed the cited vulnerable pattern exists in source.

Fix verification

fixed

baseline reproduced→ patch + rebuild →patched clean

fix.diff compiled in batch kernel build rc=0 -Werror

fix.diff compiled in batch kernel build rc=0 -Werror

↓ fix.diffcombined build rc=0

Confirmed kernel references

—

Detail

Exploit chain

none (Low severity)

Evidence (decisive lines)

Source-confirmed: carrier_detect_main[max1] OOB read when max1=-1 (msp34xx.c:744,810)

Verified recommended fix

Source-confirmed: carrier_detect_main[max1] OOB read when max1=-1 (msp34xx.c:744,810)

Verdict

Source-confirmed: carrier_detect_main[max1] OOB read when max1=-1 (msp34xx.c:744,810)