mac80211: move WEP weak IV check

I suspect the compiler will do this optimisation
anyway, but it seems cleaner to move this into
the WEP switch case.

Also make rx_h_decrypt use a local variable for
the frame_control so that we don't need to reload
the hdr variable for this after linearizing.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 16 insertions, 15 deletions

diff --git a/net/mac80211/rx.c b/net/mac80211/rx.c
index 6e2a7bcd8cb8..0ade26793918 100644
--- a/net/mac80211/rx.c
+++ b/net/mac80211/rx.c
@@ -825,6 +825,7 @@ ieee80211_rx_h_decrypt(struct ieee80211_rx_data *rx)
         ieee80211_rx_result result = RX_DROP_UNUSABLE;
         struct ieee80211_key *stakey = NULL;
         int mmie_keyidx = -1;
+        __le16 fc;
 
         /*
          * Key selection 101
@@ -866,13 +867,15 @@ ieee80211_rx_h_decrypt(struct ieee80211_rx_data *rx)
         if (rx->sta)
                 stakey = rcu_dereference(rx->sta->key);
 
-        if (!ieee80211_has_protected(hdr->frame_control))
+        fc = hdr->frame_control;
+
+        if (!ieee80211_has_protected(fc))
                 mmie_keyidx = ieee80211_get_mmie_keyidx(rx->skb);
 
         if (!is_multicast_ether_addr(hdr->addr1) && stakey) {
                 rx->key = stakey;
                 /* Skip decryption if the frame is not protected. */
-                if (!ieee80211_has_protected(hdr->frame_control))
+                if (!ieee80211_has_protected(fc))
                         return RX_CONTINUE;
         } else if (mmie_keyidx >= 0) {
                 /* Broadcast/multicast robust management frame / BIP */
@@ -884,7 +887,7 @@ ieee80211_rx_h_decrypt(struct ieee80211_rx_data *rx)
                     mmie_keyidx >= NUM_DEFAULT_KEYS + NUM_DEFAULT_MGMT_KEYS)
                         return RX_DROP_MONITOR; /* unexpected BIP keyidx */
                 rx->key = rcu_dereference(rx->sdata->keys[mmie_keyidx]);
-        } else if (!ieee80211_has_protected(hdr->frame_control)) {
+        } else if (!ieee80211_has_protected(fc)) {
                 /*
                  * The frame was not protected, so skip decryption. However, we
                  * need to set rx->key if there is a key that could have been
@@ -892,7 +895,7 @@ ieee80211_rx_h_decrypt(struct ieee80211_rx_data *rx)
                  * have been expected.
                  */
                 struct ieee80211_key *key = NULL;
-                if (ieee80211_is_mgmt(hdr->frame_control) &&
+                if (ieee80211_is_mgmt(fc) &&
                     is_multicast_ether_addr(hdr->addr1) &&
                     (key = rcu_dereference(rx->sdata->default_mgmt_key)))
                         rx->key = key;
@@ -914,7 +917,7 @@ ieee80211_rx_h_decrypt(struct ieee80211_rx_data *rx)
                     (status->flag & RX_FLAG_IV_STRIPPED))
                         return RX_CONTINUE;
 
-                hdrlen = ieee80211_hdrlen(hdr->frame_control);
+                hdrlen = ieee80211_hdrlen(fc);
 
                 if (rx->skb->len < 8 + hdrlen)
                         return RX_DROP_UNUSABLE; /* TODO: count this? */
@@ -947,19 +950,17 @@ ieee80211_rx_h_decrypt(struct ieee80211_rx_data *rx)
 
         if (skb_linearize(rx->skb))
                 return RX_DROP_UNUSABLE;
-
-        hdr = (struct ieee80211_hdr *)rx->skb->data;
-
-        /* Check for weak IVs if possible */
-        if (rx->sta && rx->key->conf.alg == ALG_WEP &&
-            ieee80211_is_data(hdr->frame_control) &&
-            (!(status->flag & RX_FLAG_IV_STRIPPED) ||
-             !(status->flag & RX_FLAG_DECRYPTED)) &&
-            ieee80211_wep_is_weak_iv(rx->skb, rx->key))
-                rx->sta->wep_weak_iv_count++;
+        /* the hdr variable is invalid now! */
 
         switch (rx->key->conf.alg) {
         case ALG_WEP:
+                /* Check for weak IVs if possible */
+                if (rx->sta && ieee80211_is_data(fc) &&
+                    (!(status->flag & RX_FLAG_IV_STRIPPED) ||
+                     !(status->flag & RX_FLAG_DECRYPTED)) &&
+                    ieee80211_wep_is_weak_iv(rx->skb, rx->key))
+                        rx->sta->wep_weak_iv_count++;
+
                 result = ieee80211_crypto_wep_decrypt(rx);
                 break;
         case ALG_TKIP: