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: NJohannes Berg <johannes.berg@intel.com>

drivers/net/wireless/rtlwifi/rtl8188ee/trx.c

@@ -452,7 +452,7 @@ bool rtl88ee_rx_query_desc(struct ieee80211_hw *hw,
 			/* During testing, hdr was NULL */
 			return false;
 		}
-		if ((ieee80211_is_robust_mgmt_frame(hdr)) &&
+		if ((_ieee80211_is_robust_mgmt_frame(hdr)) &&
 		    (ieee80211_has_protected(hdr->frame_control)))
 			rx_status->flag &= ~RX_FLAG_DECRYPTED;
 		else

drivers/net/wireless/rtlwifi/rtl8192ce/trx.c

@@ -393,7 +393,7 @@ bool rtl92ce_rx_query_desc(struct ieee80211_hw *hw,
 			/* In testing, hdr was NULL here */
 			return false;
 		}
-		if ((ieee80211_is_robust_mgmt_frame(hdr)) &&
+		if ((_ieee80211_is_robust_mgmt_frame(hdr)) &&
 		    (ieee80211_has_protected(hdr->frame_control)))
 			rx_status->flag &= ~RX_FLAG_DECRYPTED;
 		else

drivers/net/wireless/rtlwifi/rtl8192se/trx.c

@@ -310,7 +310,7 @@ bool rtl92se_rx_query_desc(struct ieee80211_hw *hw, struct rtl_stats *stats,
 			/* during testing, hdr was NULL here */
 			return false;
 		}
-		if ((ieee80211_is_robust_mgmt_frame(hdr)) &&
+		if ((_ieee80211_is_robust_mgmt_frame(hdr)) &&
 			(ieee80211_has_protected(hdr->frame_control)))
 			rx_status->flag &= ~RX_FLAG_DECRYPTED;
 		else

drivers/net/wireless/rtlwifi/rtl8723ae/trx.c

@@ -334,7 +334,7 @@ bool rtl8723ae_rx_query_desc(struct ieee80211_hw *hw,
 			/* during testing, hdr could be NULL here */
 			return false;
 		}
-		if ((ieee80211_is_robust_mgmt_frame(hdr)) &&
+		if ((_ieee80211_is_robust_mgmt_frame(hdr)) &&
 			(ieee80211_has_protected(hdr->frame_control)))
 			rx_status->flag &= ~RX_FLAG_DECRYPTED;
 		else

include/linux/ieee80211.h

@@ -2192,10 +2192,10 @@ static inline u8 *ieee80211_get_DA(struct ieee80211_hdr *hdr)
 }
 
 /**
- * ieee80211_is_robust_mgmt_frame - check if frame is a robust management frame
+ * _ieee80211_is_robust_mgmt_frame - check if frame is a robust management frame
  * @hdr: the frame (buffer must include at least the first octet of payload)
  */
-static inline bool ieee80211_is_robust_mgmt_frame(struct ieee80211_hdr *hdr)
+static inline bool _ieee80211_is_robust_mgmt_frame(struct ieee80211_hdr *hdr)
 {
 	if (ieee80211_is_disassoc(hdr->frame_control) ||
 	    ieee80211_is_deauth(hdr->frame_control))
@@ -2223,6 +2223,17 @@ static inline bool ieee80211_is_robust_mgmt_frame(struct ieee80211_hdr *hdr)
 	return false;
 }
 
+/**
+ * ieee80211_is_robust_mgmt_frame - check if skb contains a robust mgmt frame
+ * @skb: the skb containing the frame, length will be checked
+ */
+static inline bool ieee80211_is_robust_mgmt_frame(struct sk_buff *skb)
+{
+	if (skb->len < 25)
+		return false;
+	return _ieee80211_is_robust_mgmt_frame((void *)skb->data);
+}
+
 /**
  * ieee80211_is_public_action - check if frame is a public action frame
  * @hdr: the frame

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;
 	}
 

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);

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 -