Summary

initsd L511 validates init_blocksize only ==0 and >MAX_REVIVE_BLOCKSIZE; lacks DEV_BSHIFT alignment check that revive_block L84-85 applies to revive_blocksize. init_blocksize 1..511 passes validation. L520 size=init_blocksize>>DEV_BSHIFT=0; <<DEV_BSHIFT=0. L523 Malloc(0) returns ZERO_LENGTH_PTR=(-8) kern_slaballoc.c:888-890. L555 *bp->b_data!=0 derefs addr -8 -> page fault panic. L556 bcmp(bp->b_data,&bp->b_data[1],bp->b_bcount-1) b_bcount int 0-1=-1 widened size_t SIZE_MAX OOB read. VINUM_SETSTATE start_object SD[idx].init_blocksize=data->blocksize vinumstate.c:884-885 non-zero test only. Root-only. Fix: mirror revive_block validation (init_blocksize&((1<<DEV_BSHIFT)-1)) reject non-aligned.

PoC verification

Evidence pack

findings/poc/DF-1885 · 4 files

File	Type	Description	Size
fix.diff	suggested-fix	git-apply-able fix for the cited bug	743 B	view raw
VERDICT.md	verdict	source-confirmation analysis	1.0 KB	↓ raw
build.sh	build-script	N/A (source-only)	65 B	view raw
run.sh	run-script	N/A (source-only)	89 B	view raw

VERDICT.md verdict source-confirmation analysis

↓ download raw

DF-1885 VERDICT

Verdict: REPRODUCED (source-confirmed)

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

Mechanism: initsd L511 validates init_blocksize only ==0 and >MAX_REVIVE_BLOCKSIZE; lacks DEV_BSHIFT alignment check that revive_block L84-85 applies to revive_blocksize. init_blocksize 1..511 passes validation.

Citation: sys/dev/raid/vinum/vinumrevive.c:511-556

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 status (batch validation)

Applied with the 36 sibling fix.diffs of this batch in findings/poc/_batch41/all_fixes.patch; single in-guest make -j6 nativekernel KERNCONF=X86_64_GENERIC completed RC=0 with zero errors under -Werror (full log: findings/poc/_batch41/fix_build8.log). Behavior A/B intentionally skipped for this Info-tier item.

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: init_blocksize 1-511 yields size=0 -> Malloc(0)=ZERO_LENGTH_PTR deref (vinumrevive.c:511-556)

Verified recommended fix

Source-confirmed: init_blocksize 1-511 yields size=0 -> Malloc(0)=ZERO_LENGTH_PTR deref (vinumrevive.c:511-556)

Verdict