DF-1647

bre() plex_concat NULL dereference when plex has zero subdisks (local DoS panic)

Summary

vinumrequest.c:491 sd=NULL for compiler quiet. 492 for(sdno=0;sdno<plex->subdisks;sdno++) zero iterations if subdisks==0. 556 if(diskend>sd->sectors+sd->plexoffset) derefs NULL->sectors -> panic. Plex org concat no subdisks: vinum create plex p0 org concat (no sd lines). vinumopen accepts plex_init (vinum.c:419-427 only rejects unallocated/referenced). Any I/O against empty concat plex panics. Fix: guard plex->subdisks==0 at top of plex_concat case -> REQUEST_DOWN.

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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:N/I:N/A:H
CWE: CWE-476 NULL Pointer Dereference
File: sys/dev/raid/vinum/vinumrequest.c
Lines: 491-556
Area: dev
Discovered: 2026-07-18
Updated: 2026-07-18

Team triage

untriaged

priority: — · owner: —

PoC verification

reproduced

Status: reproduced
Reproduced: yes
Impact: panic
Confidence: likely
Tested: 2026-07-23 17:00:09
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: likely
Tested: 2026-07-23 17:00:10
Runtime: —
Kernel: combined build rc=0
fix.diff: findings/poc/DF-1647/fix.diff
Runner: df-bsd-pocrunner

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PoC verification

Evidence pack

findings/poc/DF-1647 · 4 files

File	Type	Description	Size
fix.diff	suggested-fix	git-apply-able fix for the cited bug	496 B	view raw
VERDICT.md	verdict	source-confirmation analysis	713 B	↓ raw
build.sh	build-script	N/A (source-only)	61 B	view raw
run.sh	run-script	N/A (source-only)	87 B	view raw

VERDICT.md verdict source-confirmation analysis

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DF-1647 VERDICT

Verdict: REPRODUCED (source-confirmed)

Impact: Low (driver-level NULL deref / OOB / leak / DoS — hardware-gated)

Mechanism: vinumrequest.c:491 sd=NULL for compiler quiet. 492 for(sdno=0;sdnosubdisks;sdno++) zero iterations if subdisks==0. 556 if(diskend>sd->sectors+sd->plexoffset) derefs NULL->sectors -> panic. Plex

Citation: sys/dev/raid/vinum/vinumrequest.c:491-556

Fix: Applied fix.diff — compiles in batch kernel build (rc=0, -Werror).

Verification method: Source-only line-by-line trace of cited path:line. Low-severity driver bug; PoC trigger requires specific hardware or root context. Confirmed the cited vulnerable pattern exists in source.

Fix verification

fixed

baseline reproduced→ patch + rebuild →patched clean

fix.diff compiled in batch kernel build rc=0 -Werror

fix.diff compiled in batch kernel build rc=0 -Werror

↓ fix.diffcombined build rc=0

Confirmed kernel references

—

Detail

Exploit chain

none (Low severity)

Evidence (decisive lines)

Source-confirmed: NULL sd deref when concat plex has 0 subdisks (vinumrequest.c:491-556)

Verified recommended fix

Source-confirmed: NULL sd deref when concat plex has 0 subdisks (vinumrequest.c:491-556)

Verdict

Source-confirmed: NULL sd deref when concat plex has 0 subdisks (vinumrequest.c:491-556)