nl80211: fix MAC address validation

commit e007b857 upstream.

MAC addresses have a fixed length. The current
policy allows passing < ETH_ALEN bytes, which
might result in reading beyond the buffer.
Signed-off-by: Eliad Peller <eliad@wizery.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

net/wireless/nl80211.c

@@ -74,8 +74,8 @@ static struct nla_policy nl80211_policy[NL80211_ATTR_MAX+1] __read_mostly = {
 	[NL80211_ATTR_IFINDEX] = { .type = NLA_U32 },
 	[NL80211_ATTR_IFNAME] = { .type = NLA_NUL_STRING, .len = IFNAMSIZ-1 },
 
-	[NL80211_ATTR_MAC] = { .type = NLA_BINARY, .len = ETH_ALEN },
-	[NL80211_ATTR_PREV_BSSID] = { .type = NLA_BINARY, .len = ETH_ALEN },
+	[NL80211_ATTR_MAC] = { .len = ETH_ALEN },
+	[NL80211_ATTR_PREV_BSSID] = { .len = ETH_ALEN },
 
 	[NL80211_ATTR_KEY] = { .type = NLA_NESTED, },
 	[NL80211_ATTR_KEY_DATA] = { .type = NLA_BINARY,