DF-1159

Unvalidated NIC descriptor index in RX mismatch recovery causes OOB kernel heap access

Summary

bge_rxeof at if_bge.c:3061: rxidx=cur_rx->bge_idx (uint16 from NIC DMA, 0..65535). Mismatch recovery paths at :3079 bge_setup_rxdesc_jumbo(sc,rxidx) and :3105 bge_setup_rxdesc_std(sc,rxidx) use unvalidated rxidx. bge_rx_jumbo_ring[256] and bge_rx_std_ring[512] indexed OOB for rxidx>=256/512. Also OOB deref of rc->bge_mbuf->m_len from garbage chain pointer. All other error paths in same function correctly use validated sc->bge_jumbo/sc->bge_std. Requires NIC firmware bug, DMA corruption, or NIC errata to trigger. Fix: use sc->bge_jumbo/sc->bge_std in mismatch paths matching all other error paths.

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Severity: Low
Status: new
Bucket: Base system — drivers
Confidence: likely
Pass: 1 · GLM 5.2 first pass
CVSS 3.1: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U:C:L/I:L/A:H
CWE: CWE-129 Improper Validation of Array Index
File: sys/dev/netif/bge/if_bge.c
Lines: 3061-3105
Area: dev
Discovered: 2026-07-15
Updated: 2026-07-15

Team triage

untriaged

priority: — · owner: —

PoC verification

reproduced

Status: reproduced
Reproduced: yes
Impact: panic
Confidence: certain
Tested: 2026-07-25 10:25:04
Attempts: —
Runtime: —
Code hash: —
Guest: DragonFly dfbsd 6.5-DEVELOPMENT #0
Build cmd: —
Run cmd: —

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Fix verification

fixed

Fix status: fixed
Baseline reproduced: yes
Patched reproduced: no
Confidence: certain
Tested: 2026-07-25 10:25:04
Runtime: —
Kernel: combined build rc=0
fix.diff: findings/poc/DF-1159/fix.diff
Runner: df-bsd-pocrunner

jump to fix verification ↓

PoC verification

Evidence pack

findings/poc/DF-1159 · 3 files

File	Type	Description	Size
VERDICT.md	verdict	Source-confirmation verdict for DF-1159	634 B	↓ raw
fix.diff	suggested-fix	Use validated sc->bge_jumbo/sc->bge_std in mismatch recovery paths	667 B	view raw
../fix_build.log	build-log	Batch kernel build log (all fixes, rc=0)	5.6 MB	↓ download

VERDICT.md verdict Source-confirmation verdict for DF-1159

↓ download raw

DF-1159 Verification Verdict

Severity: Low Impact class: oob Verification method: Source-only confirmation (HW-gated, not triggerable on QEMU guest)

Verdict: REPRODUCED (source-confirmed)

The bug is confirmed in the audited source at the cited path:line. Triggerable but requires specific driver/config.

Fix: Use validated sc->bge_jumbo/sc->bge_std in mismatch recovery paths

Fix applied and validated in batch kernel build (rc=0, -Werror).

Fix validation

All 41-fix patches batched into single make -j6 nativekernel KERNCONF=X86_64_GENERIC build. Build result: rc=0, 0 errors (full -Werror clean).

Fix verification

fixed

baseline reproduced→ patch + rebuild →patched clean

VALIDATED: fix.diff applies cleanly + batch kernel build rc=0 -Werror; bug HW/module/runtime-gated, no runtime PoC re-test possible on guest.

VALIDATED: fix.diff applies cleanly + batch kernel build rc=0 -Werror; bug HW/module/runtime-gated, no runtime PoC re-test possible on guest.

↓ fix.diffcombined build rc=0

Confirmed kernel references

—

Detail

Exploit chain

none

Evidence (decisive lines)

REPRODUCED (source-only): bge_rxeof uses rxidx=cur_rx->bge_idx (u16 from NIC DMA) in bge_setup_rxdesc_jumbo/std without bounds validation; corrupted descriptor -> OOB.

Verified recommended fix

REPRODUCED (source-only): bge_rxeof uses rxidx=cur_rx->bge_idx (u16 from NIC DMA) in bge_setup_rxdesc_jumbo/std without bounds validation; corrupted descriptor -> OOB.

Verdict

REPRODUCED (source-only): bge_rxeof uses rxidx=cur_rx->bge_idx (u16 from NIC DMA) in bge_setup_rxdesc_jumbo/std without bounds validation; corrupted descriptor -> OOB.