mac80211: add length check in ieee80211_is_robust_mgmt_frame()

A few places weren't checking that the frame passed to the
function actually has enough data even though the function
clearly documents it must have a payload byte. Make this
safer by changing the function to take an skb and checking
the length inside. The old version is preserved for now as
the rtl* drivers use it and don't have a correct skb.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>

3 files changed, 11 insertions, 13 deletions

diff --git a/net/mac80211/rx.c b/net/mac80211/rx.c
index c24ca0d..3b7a750 100644
--- a/net/mac80211/rx.c
+++ b/net/mac80211/rx.c
@@ -599,10 +599,10 @@ static int ieee80211_is_unicast_robust_mgmt_frame(struct sk_buff *skb)
 {
 	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
 
-	if (skb->len < 24 || is_multicast_ether_addr(hdr->addr1))
+	if (is_multicast_ether_addr(hdr->addr1))
 		return 0;
 
-	return ieee80211_is_robust_mgmt_frame(hdr);
+	return ieee80211_is_robust_mgmt_frame(skb);
 }
 
 
@@ -610,10 +610,10 @@ static int ieee80211_is_multicast_robust_mgmt_frame(struct sk_buff *skb)
 {
 	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
 
-	if (skb->len < 24 || !is_multicast_ether_addr(hdr->addr1))
+	if (!is_multicast_ether_addr(hdr->addr1))
 		return 0;
 
-	return ieee80211_is_robust_mgmt_frame(hdr);
+	return ieee80211_is_robust_mgmt_frame(skb);
 }
 
 
@@ -626,7 +626,7 @@ static int ieee80211_get_mmie_keyidx(struct sk_buff *skb)
 	if (skb->len < 24 + sizeof(*mmie) || !is_multicast_ether_addr(hdr->da))
 		return -1;
 
-	if (!ieee80211_is_robust_mgmt_frame((struct ieee80211_hdr *) hdr))
+	if (!ieee80211_is_robust_mgmt_frame(skb))
 		return -1; /* not a robust management frame */
 
 	mmie = (struct ieee80211_mmie *)
@@ -1845,8 +1845,7 @@ static int ieee80211_drop_unencrypted_mgmt(struct ieee80211_rx_data *rx)
 		 * having configured keys.
 		 */
 		if (unlikely(ieee80211_is_action(fc) && !rx->key &&
-			     ieee80211_is_robust_mgmt_frame(
-				     (struct ieee80211_hdr *) rx->skb->data)))
+			     ieee80211_is_robust_mgmt_frame(rx->skb)))
 			return -EACCES;
 	}
 
diff --git a/net/mac80211/tx.c b/net/mac80211/tx.c
index bb990ec..07a7f38 100644
--- a/net/mac80211/tx.c
+++ b/net/mac80211/tx.c
@@ -452,8 +452,7 @@ static int ieee80211_use_mfp(__le16 fc, struct sta_info *sta,
 	if (sta == NULL || !test_sta_flag(sta, WLAN_STA_MFP))
 		return 0;
 
-	if (!ieee80211_is_robust_mgmt_frame((struct ieee80211_hdr *)
-					    skb->data))
+	if (!ieee80211_is_robust_mgmt_frame(skb))
 		return 0;
 
 	return 1;
@@ -567,7 +566,7 @@ ieee80211_tx_h_select_key(struct ieee80211_tx_data *tx)
 		tx->key = key;
 	else if (ieee80211_is_mgmt(hdr->frame_control) &&
 		 is_multicast_ether_addr(hdr->addr1) &&
-		 ieee80211_is_robust_mgmt_frame(hdr) &&
+		 ieee80211_is_robust_mgmt_frame(tx->skb) &&
 		 (key = rcu_dereference(tx->sdata->default_mgmt_key)))
 		tx->key = key;
 	else if (is_multicast_ether_addr(hdr->addr1) &&
@@ -582,12 +581,12 @@ ieee80211_tx_h_select_key(struct ieee80211_tx_data *tx)
 		tx->key = NULL;
 	else if (tx->skb->protocol == tx->sdata->control_port_protocol)
 		tx->key = NULL;
-	else if (ieee80211_is_robust_mgmt_frame(hdr) &&
+	else if (ieee80211_is_robust_mgmt_frame(tx->skb) &&
 		 !(ieee80211_is_action(hdr->frame_control) &&
 		   tx->sta && test_sta_flag(tx->sta, WLAN_STA_MFP)))
 		tx->key = NULL;
 	else if (ieee80211_is_mgmt(hdr->frame_control) &&
-		 !ieee80211_is_robust_mgmt_frame(hdr))
+		 !ieee80211_is_robust_mgmt_frame(tx->skb))
 		tx->key = NULL;
 	else {
 		I802_DEBUG_INC(tx->local->tx_handlers_drop_unencrypted);
diff --git a/net/mac80211/wpa.c b/net/mac80211/wpa.c
index 4aed45c..b8600e3 100644
--- a/net/mac80211/wpa.c
+++ b/net/mac80211/wpa.c
@@ -494,7 +494,7 @@ ieee80211_crypto_ccmp_decrypt(struct ieee80211_rx_data *rx)
 	hdrlen = ieee80211_hdrlen(hdr->frame_control);
 
 	if (!ieee80211_is_data(hdr->frame_control) &&
-	    !ieee80211_is_robust_mgmt_frame(hdr))
+	    !ieee80211_is_robust_mgmt_frame(skb))
 		return RX_CONTINUE;
 
 	data_len = skb->len - hdrlen - IEEE80211_CCMP_HDR_LEN -