RC4 key material and S-box left unzeroed on kernel stack after encrypt/decrypt

Summary

wep_encrypt (:334) and wep_decrypt (:417): uint8_t rc4key[19] populated with composite RC4 key (3B IV + shared secret wk_key) at :345-346/:428-429 uint8_t S[256] RC4 internal state. Neither cleared before function returns (:393/:475 return without explicit_bzero). Key material persists on kernel stack until overwritten by subsequent call. WEP shared secret long-lived manually configured shared among all stations. wep_ctx wc_iv (:163) not zeroed on detach (:117). Defense-in-depth hardening gap same pattern CCMP/TKIP cross-cipher. Fix: explicit_bzero(rc4key,sizeof)+explicit_bzero(S,sizeof) before return both functions.