mac80211_hwsim: Fix memory leak in hwsim_new_radio_nl()

hwsim_new_radio_nl() now copies the name attribute in order to add a
null-terminator.  mac80211_hwsim_new_radio() (indirectly) copies it
again into the net_device structure, so the first copy is not used or
freed later.  Free the first copy before returning.

Fixes: ff4dd73dd2b4 ("mac80211_hwsim: check HWSIM_ATTR_RADIO_NAME length")
Signed-off-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

drivers/net/wireless/mac80211_hwsim.c

@@ -3108,6 +3108,7 @@ static int hwsim_new_radio_nl(struct sk_buff *msg, struct genl_info *info)
 {
 	struct hwsim_new_radio_params param = { 0 };
 	const char *hwname = NULL;
+	int ret;
 
 	param.reg_strict = info->attrs[HWSIM_ATTR_REG_STRICT_REG];
 	param.p2p_device = info->attrs[HWSIM_ATTR_SUPPORT_P2P_DEVICE];
@@ -3147,7 +3148,9 @@ static int hwsim_new_radio_nl(struct sk_buff *msg, struct genl_info *info)
 		param.regd = hwsim_world_regdom_custom[idx];
 	}
 
-	return mac80211_hwsim_new_radio(info, &param);
+	ret = mac80211_hwsim_new_radio(info, &param);
+	kfree(hwname);
+	return ret;
 }
 
 static int hwsim_del_radio_nl(struct sk_buff *msg, struct genl_info *info)