[PATCH rtw-next 2/3] wifi: rtlwifi: validate action frame size in rtl_action_proc()

[Ping-Ke Shih <pkshih@realtek.com>]

Since action frames might be malformed from RX or injected TX, validate
the size before using.

More, use struct ieee80211_mgmt to access fields of action frames instead
of counting barely.

Tested with ping on RTL8723BE. The add BA request action frames of TX/RX
can be handled properly.

Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
---
 drivers/net/wireless/realtek/rtlwifi/base.c | 17 ++++++++++-------
 1 file changed, 10 insertions(+), 7 deletions(-)

diff --git a/drivers/net/wireless/realtek/rtlwifi/base.c b/drivers/net/wireless/realtek/rtlwifi/base.c
index aad377864e73..9e98c01bb90e 100644
--- a/drivers/net/wireless/realtek/rtlwifi/base.c
+++ b/drivers/net/wireless/realtek/rtlwifi/base.c
@@ -1369,18 +1369,19 @@ bool rtl_action_proc(struct ieee80211_hw *hw, struct sk_buff *skb, u8 is_tx)
 	struct rtl_mac *mac = rtl_mac(rtl_priv(hw));
 	struct ieee80211_hdr *hdr = rtl_get_hdr(skb);
 	struct rtl_priv *rtlpriv = rtl_priv(hw);
+	struct ieee80211_mgmt *mgmt;
 	__le16 fc = rtl_get_fc(skb);
-	u8 *act = (u8 *)(((u8 *)skb->data + MAC80211_3ADDR_LEN));
-	u8 category;
 
 	if (!ieee80211_is_action(fc))
 		return true;
 
-	category = *act;
-	act++;
-	switch (category) {
+	mgmt = (void *)skb->data;
+	if (skb->len < IEEE80211_MIN_ACTION_SIZE(action_code))
+		return true;
+
+	switch (mgmt->u.action.category) {
 	case ACT_CAT_BA:
-		switch (*act) {
+		switch (mgmt->u.action.action_code) {
 		case ACT_ADDBAREQ:
 			if (mac->act_scanning)
 				return false;
@@ -1394,9 +1395,11 @@ bool rtl_action_proc(struct ieee80211_hw *hw, struct sk_buff *skb, u8 is_tx)
 				struct ieee80211_sta *sta = NULL;
 				struct rtl_sta_info *sta_entry = NULL;
 				struct rtl_tid_data *tid_data;
-				struct ieee80211_mgmt *mgmt = (void *)skb->data;
 				u16 capab = 0, tid = 0;
 
+				if (skb->len < IEEE80211_MIN_ACTION_SIZE(addba_req))
+					return true;
+
 				rcu_read_lock();
 				sta = rtl_find_sta(hw, hdr->addr3);
 				if (sta == NULL) {
-- 
2.25.1