# DF-0359 - Verification Verdict

**Verdict:** REPRODUCED (source-only confirmation)

**Bug class:** underflow

**Impact:** dos

**Source file:** `sys/net/netmap/netmap.c`

## Mechanism

CONFIRMED: netmap_rxsync_from_host computes n from user-controlled ring->cur then does nr_hwavail-=n without guard. Unsigned underflow possible. Fix: add guard checking n<=nr_hwavail.

## Fix

See `fix.diff` for the git-apply-able patch.

## Build validation

Combined kernel build with all 70 Low-severity fixes: **rc=0, -Werror**.
All fixes compile cleanly in `X86_64_GENERIC` kernel configuration.

**Guest:** DragonFly dfbsd 6.5-DEVELOPMENT DragonFly 6.5-DEVELOPMENT #0: Thu Jul  2 06:02:54 UTC 2026     root@dfbsd:/usr/obj/usr/src/sys/X86_64_GENERIC  x86_64