mac80211: fix action frame length checks

The action frame length checks are one too small, there's not just
an action code as the comment makes you believe, there's a category
code too, and the category code is required in each action frame
(hence part of IEEE80211_MIN_ACTION_SIZE).

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

net/mac80211/mesh_hwmp.c

@@ -581,6 +581,10 @@ void mesh_rx_path_sel_frame(struct ieee80211_sub_if_data *sdata,
 	size_t baselen;
 	u32 last_hop_metric;
 
+	/* need action_code */
+	if (len < IEEE80211_MIN_ACTION_SIZE + 1)
+		return;
+
 	baselen = (u8 *) mgmt->u.action.u.mesh_action.variable - (u8 *) mgmt;
 	ieee802_11_parse_elems(mgmt->u.action.u.mesh_action.variable,
 			len - baselen, &elems);

net/mac80211/mesh_plink.c

@@ -421,6 +421,10 @@ void mesh_rx_plink_frame(struct ieee80211_sub_if_data *sdata, struct ieee80211_m
 	DECLARE_MAC_BUF(mac);
 #endif
 
+	/* need action_code, aux */
+	if (len < IEEE80211_MIN_ACTION_SIZE + 3)
+		return;
+
 	if (is_multicast_ether_addr(mgmt->da)) {
 		mpl_dbg("Mesh plink: ignore frame from multicast address");
 		return;

net/mac80211/mlme.c

@@ -60,7 +60,7 @@
 
 #define ERP_INFO_USE_PROTECTION BIT(1)
 
-/* mgmt header + 1 byte action code */
+/* mgmt header + 1 byte category code */
 #define IEEE80211_MIN_ACTION_SIZE (24 + 1)
 
 #define IEEE80211_ADDBA_PARAM_POLICY_MASK 0x0002
@@ -2988,7 +2988,8 @@ static void ieee80211_rx_mgmt_action(struct ieee80211_sub_if_data *sdata,
 {
 	struct ieee80211_local *local = sdata->local;
 
-	if (len < IEEE80211_MIN_ACTION_SIZE)
+	/* all categories we currently handle have action_code */
+	if (len < IEEE80211_MIN_ACTION_SIZE + 1)
 		return;
 
 	switch (mgmt->u.action.category) {