Summary

ath_rate_update L246-269: amn->amn_tx_rix0=sc->sc_rixmap[ni->ni_txrate] then rt->info[amn_tx_rix0].rateCode. sc_rixmap returns 0xff sentinel for rates absent from current PHY mode table (if_ath.c:6200 memset 0xff). rt->info[64] so index 0xff reads ~3036 bytes past end of HAL_RATE_TABLE. Same for rate1 L256-258 and rate2 L265-267 via sc_rixmap[rates[rate]&IEEE80211_RATE_VAL]. Reachable: IBSS orphaned node with rate not in current PHY mode; infrastructure mode after channel/mode switch on active association. Source comments L342-347 acknowledge unmappable rates. Sibling sample.c L649-656 guards with if(rix<0||rix>=rt->rateCount); amrr omits. Attacker: unauth WiFi peer within radio range ath(4) with amrr. Impact: OOB read kernel .data (static rate tables adjacent); rateCode in radiotap TX headers observable by monitor mode (limited info leak); kmalloc rate tables -> page fault panic. Fix: validate rix<rt->rateCount before indexing rt->info[rix] at all 3 sites mirroring sample.c.

PoC verification

Evidence pack

findings/poc/DF-1931 · 4 files

File	Type	Description	Size
fix.diff	suggested-fix	git-apply-able fix for the cited bug	579 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-1931 VERDICT

Verdict: REPRODUCED (source-confirmed)

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

Mechanism: ath_rate_update L246-269: amn->amn_tx_rix0=sc->sc_rixmap[ni->ni_txrate] then rt->info[amn_tx_rix0].rateCode. sc_rixmap returns 0xff sentinel for rates absent from current PHY mode table (if_ath.c:6200

Citation: sys/dev/netif/ath/ath_rate/amrr/amrr.c:246-269

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: rt->info[0xff] OOB read via sc_rixmap sentinel (amrr.c:246-269)

Verified recommended fix

Source-confirmed: rt->info[0xff] OOB read via sc_rixmap sentinel (amrr.c:246-269)

Verdict