mac80211: parse Timeout Interval Element using a struct

Instead of open-coding the accesses and length check do
the length check in the IE parser and assign a struct
pointer for use in the remaining code.

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

4 files changed, 18 insertions, 7 deletions

diff --git a/include/linux/ieee80211.h b/include/linux/ieee80211.h
index d10b5bba3268..e46fea8b972e 100644
--- a/include/linux/ieee80211.h
+++ b/include/linux/ieee80211.h
@@ -1955,6 +1955,16 @@ enum ieee80211_timeout_interval_type {
         WLAN_TIMEOUT_ASSOC_COMEBACK = 3 /* 802.11w */,
 };
 
+/**
+ * struct ieee80211_timeout_interval_ie - Timeout Interval element
+ * @type: type, see &enum ieee80211_timeout_interval_type
+ * @value: timeout interval value
+ */
+struct ieee80211_timeout_interval_ie {
+        u8 type;
+        __le32 value;
+} __packed;
+
 /* BACK action code */
 enum ieee80211_back_actioncode {
         WLAN_ACTION_ADDBA_REQ = 0,
diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index 6ad019d32623..c783e996bcce 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -1180,7 +1180,7 @@ struct ieee802_11_elems {
         const struct ieee80211_channel_sw_ie *ch_switch_ie;
         const u8 *country_elem;
         const u8 *pwr_constr_elem;
-        const u8 *timeout_int;
+        const struct ieee80211_timeout_interval_ie *timeout_int;
         const u8 *opmode_notif;
 
         /* length of them, respectively */
@@ -1198,7 +1198,6 @@ struct ieee802_11_elems {
         u8 prep_len;
         u8 perr_len;
         u8 country_elem_len;
-        u8 timeout_int_len;
 
         /* whether a parse error occurred while retrieving these elements */
         bool parse_error;
diff --git a/net/mac80211/mlme.c b/net/mac80211/mlme.c
index 157d951df7a4..304d6cfc6250 100644
--- a/net/mac80211/mlme.c
+++ b/net/mac80211/mlme.c
@@ -2629,10 +2629,10 @@ ieee80211_rx_mgmt_assoc_resp(struct ieee80211_sub_if_data *sdata,
         ieee802_11_parse_elems(pos, len - (pos - (u8 *) mgmt), &elems);
 
         if (status_code == WLAN_STATUS_ASSOC_REJECTED_TEMPORARILY &&
-            elems.timeout_int && elems.timeout_int_len == 5 &&
-            elems.timeout_int[0] == WLAN_TIMEOUT_ASSOC_COMEBACK) {
+            elems.timeout_int &&
+            elems.timeout_int->type == WLAN_TIMEOUT_ASSOC_COMEBACK) {
                 u32 tu, ms;
-                tu = get_unaligned_le32(elems.timeout_int + 1);
+                tu = le32_to_cpu(elems.timeout_int->value);
                 ms = tu * 1024 / 1000;
                 sdata_info(sdata,
                            "%pM rejected association temporarily; comeback duration %u TU (%u ms)\n",
diff --git a/net/mac80211/util.c b/net/mac80211/util.c
index 4839dec5c9ac..f9581c6378ae 100644
--- a/net/mac80211/util.c
+++ b/net/mac80211/util.c
@@ -874,8 +874,10 @@ u32 ieee802_11_parse_elems_crc(u8 *start, size_t len,
                         elems->pwr_constr_elem = pos;
                         break;
                 case WLAN_EID_TIMEOUT_INTERVAL:
-                        elems->timeout_int = pos;
-                        elems->timeout_int_len = elen;
+                        if (elen >= sizeof(struct ieee80211_timeout_interval_ie))
+                                elems->timeout_int = (void *)pos;
+                        else
+                                elem_parse_failed = true;
                         break;
                 default:
                         break;