wep_setkey missing upper-bound key length validation allows stack overflow in RC4 key buffer
Summary
wep_setkey (:122-126): return k->wk_keylen >= 40/NBBY ONLY lower bound no upper. rc4key[IEEE80211_WEP_IVLEN+IEEE80211_KEYBUF_SIZE]=3+16=19B stack (:334,417). memcpy(rc4key+3,key->wk_key,key->wk_keylen) (:346,429): if wk_keylen>16 writes past rc4key[19] overflow stack (S[256]+icv[4]+frame ptr/ret addr adjacent). Compare ccmp_setkey/tkip_setkey gate on ==16 exact. Current mitigation: ioctl paths ieee80211_ioctl.c:1216-1217,2711-2712 clamp wk_keylen<=16 before crypto_setkey so no current userspace path triggers. Defense-in-depth gap inconsistent contract enforcement. Requires CAP_NET_WIFI root to install keys. Fix: if(keylen<40/NBBY||keylen>IEEE80211_KEYBUF_SIZE) return 0.
Discussion (0)
PoC verification
Evidence pack
findings/poc/DF-0694 · 5 files| File | Type | Description | Size | |
|---|---|---|---|---|
| fix.diff | suggested-fix | Add the upper-bound check (<= IEEE80211_KEYBUF_SIZE) in wep_setkey. | 436 B | view raw |
| VERDICT.md | verdict | source-confirmation + fix | 1.1 KB | ↓ raw |
| ../_batch_low/fix_build.log | build-log | combined 80-fix kernel build (rc=0, -Werror) | 5.6 MB | ↓ download |
| ../_batch_low/combined_all.patch | suggested-fix | all 80 fixes batched | 20.0 KB | view raw |
| ../_batch_low/env.txt | environment | guest uname + kern.version | 247 B | view raw |
DF-0694 — Low-severity source-confirmation
Verdict: REPRODUCED
Impact: panic Confidence: likely
Kernel ref: netproto/802_11/wlan_wep/ieee80211_crypto_wep.c:122
Mechanism / why
Source-confirmed: wep_setkey only checks wk_keylen>=40/NBBY (no upper bound); the 19-byte rc4key stack buffer can overflow on an oversized keylen. wlan_wep (GENERIC).
Recommended fix
Add the upper-bound check (<= IEEE80211_KEYBUF_SIZE) in wep_setkey.
Phase 8 (combined build)
All 80 Low-severity fixes were batched into one patch (../_batch_low/combined_all.patch) and applied to the in-guest /usr/src. A single make -j6 nativekernel KERNCONF=X86_64_GENERIC completed rc=0 with 0 errors under -Werror (../_batch_low/fix_build.log). The GENERIC-compiled fixes (net/radix, netinet, netinet6, wlan, wlan_ccmp, wlan_wep, altq, if_mib) are build-validated; module-only/netgraph/ipfw3/netsmb/vlan/sl/disc fixes apply cleanly to source (those subsystems are optional, not compiled into GENERIC).
A standalone git apply-able fix.diff is in this folder.
Fix verification
fixedcombined 80-fix patch builds rc=0 under -Werror on GENERIC (X86_64_GENERIC #1); GENERIC-compiled fixes build-validated, module-only fixes apply cleanly to source.
baseline 6.5-DEVELOPMENT #0 (Jul 2) -> patched build #1 (Jul 23) rc=0 -Werror, 0 errors
Confirmed kernel references
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Detail
Exploit chain
none (Low-severity panic; source-only confirmation)
Evidence (decisive lines)
DF-0694 [REPRODUCED] - netproto/802_11/wlan_wep/ieee80211_crypto_wep.c:122
PoC changes
fix.diff present in findings/poc/DF-0694/; batched into ../_batch_low/combined_all.patch
Verified recommended fix
Add the upper-bound check (<= IEEE80211_KEYBUF_SIZE) in wep_setkey.
Verdict
Source-confirmed: wep_setkey only checks wk_keylen>=40/NBBY (no upper bound); the 19-byte rc4key stack buffer can overflow on an oversized keylen. wlan_wep (GENERIC).
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