DF-4921

Parent-NIC softc type confusion gated only by 4-char driver-name prefix (strncmp "stge")

Summary

4-char prefix match + blind stge_softc cast to read sc_rev - a hypothetical stge* driver would be misread. No in-tree impact; FreeBSD eliminated the pattern via MIIF_PHYPRIV0. Flag-based fix.

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Severity: Info
Status: new
Bucket: Kernel memory corruption (UAF / OOB write)
Confidence: certain
Pass: 2 · GLM 5.3 second pass
CVSS 3.1: CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:N
CWE: CWE-843
File: sys/dev/netif/mii_layer/ip1000phy.c
Lines: 435-439
Area: dev
Discovered: 2026-09-25
Updated: 2026-09-25

Team triage

untriaged

priority: — · owner: —

PoC verification

untested

Status: untested
Reproduced: no
Impact: none
Confidence: certain
Tested: 2026-09-25 03:03:36
Attempts: 0
Runtime: —
Code hash: —
Guest: —
Build cmd: —
Run cmd: —

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Fix verification

not_testable

Fix status: not_testable
Baseline reproduced: —
Patched reproduced: —
Confidence: certain
Tested: 2026-09-25 03:03:37
Runtime: —
Kernel: per-fix-DF-4921
fix.diff: findings/poc/DF-4921/fix.diff
Runner: df-bsd-reviewer

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PoC verification

Evidence pack

findings/poc/DF-4921 · 1 files

File	Type	Description	Size
verdict.json	file		873 B	view raw

Fix verification

not_testable

per-fix-DF-4921

Confirmed kernel references

sys/dev/netif/mii_layer/ip1000phy.c:435-439

Detail

Exploit chain

none in-tree (requires a second stge-prefixed driver)

Evidence (decisive lines)

findings/poc/DF-4921/ (this verdict)

Verdict

Latent hardening (Info): ip1000phy_reset matches the parent driver by a 4-character strncmp against the name 'stge' then blind-casts the parent softc to struct stge_softc * to read sc_rev - any hypothetical future driver whose name begins with stge and which parents an IP1000A PHY gets its softc misread at that offset. No in-tree impact (only stge matches today; loading a driver needs root). FreeBSD eliminated exactly this pattern via MIIF_PHYPRIV0 plumbing. Flag-based fix.