# PoC DF-1520: ath_hal_getregdump OOB input-array read (output-bounded loop)

**Class:** Kernel OOB read of regs[] input array
**Cited site:** `sys/dev/netif/ath/ath_hal/ah.c:848-868, 890-892`

## Reproduction status

HW/module gated — **cannot be live-triggered on the audit QEMU guest.**

The audit guest has only virtio + PIIX3 PCI devices (`pciconf -lv` shows no
AMD/Intel GPU, no ath NIC, no AdvanSys SCSI, no mfi/tws/mrsas RAID, etc.),
so the cited code path is not reachable at runtime on this guest.

The bug is **confirmed at the source level** by tracing the cited path:line
in `sys/dev/netif/ath/ath_hal/ah.c` and confirming the vulnerable code is
present in the master DEV kernel tree. The `fix.diff` in this folder is
validated to apply cleanly and compile under `-Werror` (see `VERDICT.md`).

## Mechanism

ath_hal_getregdump loop condition depends on space (output buffer size) but body reads regs[i].start/end with NO bound on i vs the input array size. ath_hal_getdiagstate at 890-892 invokes it without forwarding argsize; SIOCGATHDIAG user path supplies the output size, the input regs[] is whatever the user passed.

## Realistic impact ceiling (on suitable HW)

kernel OOB read of attacker-supplied input buffer (info leak / crash)

## Fix

In ath_hal_getdiagstate HAL_DIAG_REGS, require non-NULL args + non-zero argsize before invoking ath_hal_getregdump.

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

## How to validate the fix

```sh
scp -F dfbsd-qemu/config fix.diff dfbsd:/root/DF-1520.diff
ssh -F dfbsd-qemu/config dfbsd 'cd /usr/src && patch -p1 --forward < /root/DF-1520.diff'
ssh -F dfbsd-qemu/config dfbsd 'cd /usr/src && make -j6 nativekernel KERNCONF=X86_64_GENERIC'
# rc=0 expected; see fix_apply.log + fix_build.log in this folder.
```