Summary

ata-all.c:462 kmalloc(ioc_request->count=0, M_ATA, M_NULLOK). kmalloc(0) returns ZERO_LENGTH_PTR ((void*)-8) per kern_slaballoc.c:888-891. Non-NULL so NULL check passes. 489 request->data=ZERO_LENGTH_PTR. 498 ata_queue_request dispatches to lowlevel DMA load with data=(void*)-8 bytecount=0. Hardware-dependent panic or silent. Operator group. Fix: reject count<=0 || count>MAXPHYS.

PoC verification

Evidence pack

findings/poc/DF-1644 · 4 files

File	Type	Description	Size
fix.diff	suggested-fix	git-apply-able fix for the cited bug	395 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-1644 VERDICT

Verdict: REPRODUCED (source-confirmed)

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

Mechanism: ata-all.c:462 kmalloc(ioc_request->count=0, M_ATA, M_NULLOK). kmalloc(0) returns ZERO_LENGTH_PTR ((void*)-8) per kern_slaballoc.c:888-891. Non-NULL so NULL check passes. 489 request->data=ZERO_LENGTH_

Citation: sys/dev/disk/nata/ata-all.c:462-498

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: count==0 passes ZERO_LENGTH_PTR as DMA data (ata-all.c:462-498)

Verified recommended fix

Source-confirmed: count==0 passes ZERO_LENGTH_PTR as DMA data (ata-all.c:462-498)

Verdict