cfg80211: fix regulatory NULL dereference

commit de3584bd upstream.

By the time userspace returns with a response to
the regulatory domain request, the wiphy causing
the request might have gone away. If this is so,
reject the update but mark the request as having
been processed anyway.

Cc: Luis R. Rodriguez <lrodriguez@qca.qualcomm.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

net/wireless/reg.c

@@ -2026,6 +2026,10 @@ static int __set_regdom(const struct ieee80211_regdomain *rd)
 	}
 
 	request_wiphy = wiphy_idx_to_wiphy(last_request->wiphy_idx);
+	if (!request_wiphy) {
+		reg_set_request_processed();
+		return -ENODEV;
+	}
 
 	if (!last_request->intersect) {
 		int r;