mac80211: fix a potential NULL access in ieee80211_crypto_hw_decrypt

The NULL pointer access could happen when ieee80211_crypto_hw_decrypt
is called from ieee80211_rx_h_decrypt with the following condition:
1. rx->key->conf.cipher is not WEP, CCMP, TKIP or AES_CMAC
2. rx->sta is NULL

When ieee80211_crypto_hw_decrypt is called, it verifies
rx->sta->cipher_scheme and it will cause Oops if rx->sta is NULL.

This path adds an addirional rx->sta == NULL verification in
ieee80211_crypto_hw_decrypt for this case.

Signed-off-by: Max Stepanov <Max.Stepanov@intel.com>
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

diff --git a/net/mac80211/wpa.c b/net/mac80211/wpa.c
index 9b3dcc201145dd3942bf30771e1638ea973759f7..f7d4ca4c46e0bf68c6232d339d4b54f7934798ba 100644 (file)
--- a/net/mac80211/wpa.c
+++ b/net/mac80211/wpa.c
@@ -811,7 +811,7 @@ ieee80211_crypto_hw_encrypt(struct ieee80211_tx_data *tx)
 ieee80211_rx_result
 ieee80211_crypto_hw_decrypt(struct ieee80211_rx_data *rx)
 {
-       if (rx->sta->cipher_scheme)
+       if (rx->sta && rx->sta->cipher_scheme)
                return ieee80211_crypto_cs_decrypt(rx);
 
        return RX_DROP_UNUSABLE;