ethtool: tsconfig: fix reply error handling

A couple of trivial bugs in error handling in tsconfig_send_reply().
If we failed to allocate rskb we need to set the error.
If we did allocate it but failed to send it - we need to remember
to free it.

Fixes: 6e9e2ee ("net: ethtool: Add support for tsconfig command to get/set hwtstamp config")
Reviewed-by: Vadim Fedorenko <vadim.fedorenko@linux.dev>
Reviewed-by: Kory Maincent <kory.maincent@bootlin.com>
Link: https://patch.msgid.link/20260526153533.2779187-3-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Author: kuba-moo

net/ethtool/tsconfig.c

@@ -224,16 +224,21 @@ static int tsconfig_send_reply(struct net_device *dev, struct genl_info *info)
 	reply_len = ret + ethnl_reply_header_size();
 	rskb = ethnl_reply_init(reply_len, dev, ETHTOOL_MSG_TSCONFIG_SET_REPLY,
 				ETHTOOL_A_TSCONFIG_HEADER, info, &reply_payload);
-	if (!rskb)
+	if (!rskb) {
+		ret = -ENOMEM;
 		goto err_cleanup;
+	}
 
 	ret = tsconfig_fill_reply(rskb, &req_info->base, &reply_data->base);
 	if (ret < 0)
-		goto err_cleanup;
+		goto err_free_msg;
 
 	genlmsg_end(rskb, reply_payload);
 	ret = genlmsg_reply(rskb, info);
+	rskb = NULL;
 
+err_free_msg:
+	nlmsg_free(rskb);
 err_cleanup:
 	kfree(reply_data);
 	kfree(req_info);