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.

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	1.0 KB	↓ raw
build.sh	build-script	N/A (source-only)	65 B	view raw
run.sh	run-script	N/A (source-only)	89 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 status (batch validation)

Applied with the 36 sibling fix.diffs of this batch in findings/poc/_batch41/all_fixes.patch; single in-guest make -j6 nativekernel KERNCONF=X86_64_GENERIC completed RC=0 with zero errors under -Werror (full log: findings/poc/_batch41/fix_build8.log). Behavior A/B intentionally skipped for this Info-tier item.

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