Summary

atmel_mxt.c:418 sc->cmdprocobj = mxt_findobject(T6) NO NULL check (only msgprocobj T5 checked at 417-423). 437 init_device success -> atmel_reset_device -> 983 mxt_write_object_off(sc, sc->cmdprocobj, ...) derefs obj->start_pos_lsb -> NULL page fault panic. Poll thread reset path at 941 same unchecked call. Attacker: malicious I2C peripheral at 0x4A reporting T5 but omitting T6 -> kernel panic at attach. Fix: require cmdprocobj!=NULL in init_device + NULL guard in atmel_reset_device.

PoC verification

Evidence pack

findings/poc/DF-1623 · 4 files

File	Type	Description	Size
fix.diff	suggested-fix	git-apply-able fix for the cited bug	551 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-1623 VERDICT

Verdict: REPRODUCED (source-confirmed)

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

Mechanism: atmel_mxt.c:418 sc->cmdprocobj = mxt_findobject(T6) NO NULL check (only msgprocobj T5 checked at 417-423). 437 init_device success -> atmel_reset_device -> 983 mxt_write_object_off(sc, sc->cmdprocobj,

Citation: sys/dev/smbus/atmel_mxt/atmel_mxt.c:418-983

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: cmdprocobj NULL deref when T6 object missing (atmel_mxt.c:418-425,983)

Verified recommended fix

Source-confirmed: cmdprocobj NULL deref when T6 object missing (atmel_mxt.c:418-425,983)

Verdict