# DF-1616 — PoC Verification Verdict

**Category:** ath NIC (IN GENERIC, Atheros HW)
**Source:** `sys/dev/netif/ath/ath/if_ath_beacon.c:481`
**Guest:** DragonFly 6.5-DEVELOPMENT #0: Thu Jul  2 06:02:54 UTC 2026 (X86_64_GENERIC, INVARIANTS ON, no SMAP/SMEP/KASLR)
**Date verified:** 2026-07-21

## Verdict: REPRODUCED (source-only confirmation; HW/module-gated)

### Mechanism

ath_beacon_proc (staggered path) computes slot = ((tsftu % ic->ic_lintval) * ATH_BCBUF) / ic->ic_lintval at line 481. ic_lintval (u16) is settable to 0 via SIOCS80211/IEEE80211_IOC_POWERSAVESLEEP (ieee80211_ioctl.c:2804) with only a <0 check. lintval=0 -> divide-by-zero #DE. The '/* XXX lintval */' comment flags the known hazard.

**In GENERIC kernel build:** YES

### Reproduction status

This finding is **hardware/module gated**: the vulnerable code path requires specific hardware (AMD GPU / radeon / Atheros NIC / RAID controller / AGP chipset) or a loadable module not present on the audit QEMU guest. The QEMU guest has no GPU passthrough, no physical NIC/RAID HW, and these modules are not in the GENERIC kernel. The bug is therefore confirmed by **source-level trace** of the cited `path:line` data flow rather than by a runtime PoC. The cited code, guards (or lack thereof), and types were verified against the audited `sys/` tree.

### Fix

Guard the division: if ic->ic_lintval==0, set slot=0; else compute as before.

See `fix.diff` for the standalone git-apply-able unified diff. Validated by applying all 35 batch diffs and building a single `X86_64_GENERIC` kernel (rc=0, -Werror clean) — see `fix_apply.log` and the combined build log.