nl80211: Fix get_inact_sec() returning -1 on failure

This commit fixes the nl80211 driver call get_inact_sec() to return -1
when STA inactivity time retrieval fails in i802_read_sta_data().

This was intended to be handled by initalizing the inactive_msec member
to -1 but i802_read_sta_data() assumes the data parameter is
uninitialized and memsets the entire structure, neutralizing the attempt
to distinguish between no value (-1) and a time value of 0.

This is fixed by now requiring i802_read_sta_data() callers to
initialize the data structure first (allowing get_inact_sec() to use
-1). This is a safe change because it does not change any driver API
behavior and only affects one other static function in driver_nl80211.c

Signed-off-by: Joel Cunningham <joel.cunningham@me.com>

src/drivers/driver_nl80211.c

@@ -5647,8 +5647,6 @@ static int i802_read_sta_data(struct i802_bss *bss,
 {
 	struct nl_msg *msg;
 
-	os_memset(data, 0, sizeof(*data));
-
 	if (!(msg = nl80211_bss_msg(bss, 0, NL80211_CMD_GET_STATION)) ||
 	    nla_put(msg, NL80211_ATTR_MAC, ETH_ALEN, addr)) {
 		nlmsg_free(msg);
@@ -5754,6 +5752,7 @@ static int i802_get_inact_sec(void *priv, const u8 *addr)
 	struct hostap_sta_driver_data data;
 	int ret;
 
+	os_memset(&data, 0, sizeof(data));
 	data.inactive_msec = (unsigned long) -1;
 	ret = i802_read_sta_data(priv, &data, addr);
 	if (ret == -ENOENT)
@@ -7756,6 +7755,8 @@ static int driver_nl80211_read_sta_data(void *priv,
 					const u8 *addr)
 {
 	struct i802_bss *bss = priv;
+
+	os_memset(data, 0, sizeof(*data));
 	return i802_read_sta_data(bss, data, addr);
 }