Summary

tws_init_connect L188-208: tws_poll4_response returns unexpected reqid or TWS_INVALID_REQID -> return(FAILURE) but never marks req->state=TWS_REQ_STATE_FREE. tws_get_request(TWS_INTERNAL_CMD_REQ) returns singleton &sc->reqs[0] tws.c:752 only succeeds when state FREE. One init_connect failure permanently bricks all future internal commands including controller reset recovery tws_cam.c:1263 and post-reset re-init tws.c:366/711. tws_reinit calls init_connect during recovery so first reset that loses response-queue race leaks slot breaks all subsequent recoveries. tws_poll4_response returns TWS_INVALID_REQID on 60s timeout reachable for slow/stuck controller. Attacker: PCI-passthrough/malicious firmware stays silent. Fix: req->state=TWS_REQ_STATE_FREE in error branch.

PoC verification

Evidence pack

findings/poc/DF-1926 · 4 files

File	Type	Description	Size
fix.diff	suggested-fix	git-apply-able fix for the cited bug	469 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-1926 VERDICT

Verdict: REPRODUCED (source-confirmed)

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

Mechanism: tws_init_connect L188-208: tws_poll4_response returns unexpected reqid or TWS_INVALID_REQID -> return(FAILURE) but never marks req->state=TWS_REQ_STATE_FREE. tws_get_request(TWS_INTERNAL_CMD_REQ) retu

Citation: sys/dev/raid/tws/tws_hdm.c:188-207

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_connect failure doesn't free singleton req slot (tws_hdm.c:188-207)

Verified recommended fix

Source-confirmed: init_connect failure doesn't free singleton req slot (tws_hdm.c:188-207)

Verdict