DF-4574

adw_init_chip restores the saved BIOS image to the wrong LRAM base (addr + ADW_MC_BIOSLEN instead of addr + ADW_MC_BIOSMEM): 16-byte-shifted restore smears BIOS bytes over microcode variables 0x9C/0x9E and leaves 0x40-0x4F clobbered

Summary

The save loop reads ADW_MC_BIOSMEM+addr (0x40-0x8F) but the restore writes ADW_MC_BIOSLEN+addr (0x50-0x9F) - a +0x10 shifted restore: bytes land on the microcode's WDTR_ABLE/SDTR_ABLE (never rewritten afterward) while 0x40-0x4F keeps firmware bytes. Chip-internal negotiation misbehavior on the EEPROM-checksum-failed corner path; no host memory impact. Same-constant fix.

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Severity: Info
Status: new
Bucket: Base system — drivers
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-682
File: sys/dev/disk/advansys/adwlib.c
Lines: 353-484
Area: dev
Discovered: 2026-09-21
Updated: 2026-09-21

Team triage

untriaged

priority: — · owner: —

PoC verification

untested

Status: untested
Reproduced: no
Impact: Chip-internal correctness only: WDTR_ABLE/SDTR_ABLE LRAM words hold arbitrary BIOS bytes (negotiation misbehavior on the EEPROM-checksum-failed corner); no host memory impact
Confidence: certain
Tested: 2026-09-21 19:54:52
Attempts: 0
Runtime: —
Code hash: —
Guest: —
Build cmd: —
Run cmd: —

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Fix verification

not_testable

Fix status: not_testable
Baseline reproduced: no
Patched reproduced: no
Confidence: certain
Tested: 2026-09-21 19:54:52
Runtime: —
Kernel: per-fix-DF-4574
fix.diff: findings/poc/DF-4574/fix.diff
Runner: df-bsd-reviewer

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PoC verification

Evidence pack

findings/poc/DF-4574 · 1 files

File	Type	Description	Size
verdict.json	file		1018 B	view raw

Fix verification

not_testable

baseline no→ patch + rebuild →patched clean

not_testable: hardware absent from guest

fix in finding markdown

per-fix-DF-4574

Confirmed kernel references

Detail

Exploit chain

[]

Evidence (decisive lines)

Restore loop uses ADW_MC_BIOSLEN (a length) as the base where the save loop used ADW_MC_BIOSMEM - +0x10 shifted restore smears over microcode vars. Same-constant fix.

Verdict

not_run: requires AdvanSys card + failed EEPROM checksum