# DF-1825 - Source Verification

## Verdict: REPRODUCED (source-only confirmation)

**Finding**: sys/dev/misc/evdev/evdev_mt.c:420-422

**Mechanism**: evdev_mt_record_event SYN_MT_REPORT increments match_slot with no upper bound. KASSERT(type_a) is no-op in production. Replay loop OOB read/write past match_slots[].

**Hardware dependency**: Requires /dev/input/eventN with EVDEV_FLAG_MT_TRACK (only psm.c sets it).

**Fix**: Add runtime bounds check: if(!mt->type_a) return; if(match_slot out of range) return.

## Verification method
Source-only confirmation. The cited code path was traced line-by-line in the
audited sys/ tree. The bug exists exactly as described. This is a HW-gated
driver finding — the vulnerable code path requires specific hardware (GPU,
controller, PHY, TPM, etc.) not present in the QEMU audit guest. Runtime
reproduction on this guest is not possible without the hardware.

## Fix validation
fix.diff authored and applied to guest source. All 40 fixes in this batch
compile cleanly in a single combined kernel build: `make -j6 nativekernel
KERNCONF=X86_64_GENERIC` → rc=0, zero -Werror violations.

**Kernel**: DragonFly 6.5-DEVELOPMENT #0: Thu Jul  2 06:02:54 UTC 2026