From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-10.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 49C63C433E5 for ; Mon, 20 Jul 2020 15:55:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 199452065E for ; Mon, 20 Jul 2020 15:55:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1595260554; bh=/8OZCy/0KMlUsqPtaxFSHndILlRwA5ZBFrl1lWVTsh4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=Hwly1pZcF1sCcsyewN35PMWi3DWZYDYpazOVjCI7D0rPBer8Xp91htUz5EnRGntuX RCOSWgiganyKSrnQ8v5GQ+6shglX1Kgi5TCaKQqPUp47wYAkEouh3t5zUBatcpqYIU QX1/aVJ2c8YdhUBLglcRIpeFUXOIMaXhCHpwbSeo= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731721AbgGTPzx (ORCPT ); Mon, 20 Jul 2020 11:55:53 -0400 Received: from mail.kernel.org ([198.145.29.99]:55164 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731732AbgGTPzw (ORCPT ); Mon, 20 Jul 2020 11:55:52 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id AD2892065E; Mon, 20 Jul 2020 15:55:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1595260552; bh=/8OZCy/0KMlUsqPtaxFSHndILlRwA5ZBFrl1lWVTsh4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=OBdeIFhuR1vFWlLrJpoGxBoYauZGttLVJ6oQlERYDGUhLFkqjUM33tU/ldXzSk5gy 0SWo5IFGsB3Fv/91xmgj6/bhTh3T8ssJjlAKMYjYOvEd4+LUC6J0eeQQg0zl+xdawR tcJBaPdjcEzZRhx89kuQYUwH+Rg2PHTjiqazV9G8= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Hangbin Liu , Xin Long , James Chapman , "David S. Miller" Subject: [PATCH 5.4 010/215] l2tp: remove skb_dst_set() from l2tp_xmit_skb() Date: Mon, 20 Jul 2020 17:34:52 +0200 Message-Id: <20200720152820.654695945@linuxfoundation.org> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20200720152820.122442056@linuxfoundation.org> References: <20200720152820.122442056@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Xin Long [ Upstream commit 27d53323664c549b5bb2dfaaf6f7ad6e0376a64e ] In the tx path of l2tp, l2tp_xmit_skb() calls skb_dst_set() to set skb's dst. However, it will eventually call inet6_csk_xmit() or ip_queue_xmit() where skb's dst will be overwritten by: skb_dst_set_noref(skb, dst); without releasing the old dst in skb. Then it causes dst/dev refcnt leak: unregister_netdevice: waiting for eth0 to become free. Usage count = 1 This can be reproduced by simply running: # modprobe l2tp_eth && modprobe l2tp_ip # sh ./tools/testing/selftests/net/l2tp.sh So before going to inet6_csk_xmit() or ip_queue_xmit(), skb's dst should be dropped. This patch is to fix it by removing skb_dst_set() from l2tp_xmit_skb() and moving skb_dst_drop() into l2tp_xmit_core(). Fixes: 3557baabf280 ("[L2TP]: PPP over L2TP driver core") Reported-by: Hangbin Liu Signed-off-by: Xin Long Acked-by: James Chapman Tested-by: James Chapman Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/l2tp/l2tp_core.c | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-) --- a/net/l2tp/l2tp_core.c +++ b/net/l2tp/l2tp_core.c @@ -1030,6 +1030,7 @@ static void l2tp_xmit_core(struct l2tp_s /* Queue the packet to IP for output */ skb->ignore_df = 1; + skb_dst_drop(skb); #if IS_ENABLED(CONFIG_IPV6) if (l2tp_sk_is_v6(tunnel->sock)) error = inet6_csk_xmit(tunnel->sock, skb, NULL); @@ -1101,10 +1102,6 @@ int l2tp_xmit_skb(struct l2tp_session *s goto out_unlock; } - /* Get routing info from the tunnel socket */ - skb_dst_drop(skb); - skb_dst_set(skb, sk_dst_check(sk, 0)); - inet = inet_sk(sk); fl = &inet->cork.fl; switch (tunnel->encap) {