From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751809AbcBOCMY (ORCPT ); Sun, 14 Feb 2016 21:12:24 -0500 Received: from mail.passe0815.de ([188.40.49.9]:35497 "EHLO mail.passe0815.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751720AbcBOCMV (ORCPT ); Sun, 14 Feb 2016 21:12:21 -0500 X-Greylist: delayed 304 seconds by postgrey-1.27 at vger.kernel.org; Sun, 14 Feb 2016 21:12:20 EST From: =?UTF-8?q?Linus=20L=C3=BCssing?= To: netdev@vger.kernel.org Cc: "David S . Miller" , Stephen Hemminger , bridge@lists.linux-foundation.org, linux-kernel@vger.kernel.org, "Steinar H . Gunderson" , =?UTF-8?q?=C3=81lvaro=20Fern=C3=A1ndez=20Rojas?= , Tom Herbert , =?UTF-8?q?Linus=20L=C3=BCssing?= Subject: [PATCH] net: fix bridge multicast packet checksum validation Date: Mon, 15 Feb 2016 03:07:06 +0100 Message-Id: <1455502026-23144-1-git-send-email-linus.luessing@c0d3.blue> X-Mailer: git-send-email 2.7.0 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-GPG-Mailgate: Not encrypted, public key not found Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org We need to update the skb->csum after pulling the skb, otherwise checksum validation will fail. This fixes multicast packet loss for bridges and splats like the following: [...] [ 43.986968] eth0: hw csum failure [ 43.990344] CPU: 3 PID: 0 Comm: swapper/3 Not tainted 4.4.0 #2 [ 43.996193] Hardware name: BCM2709 [ 43.999647] [<800204e0>] (unwind_backtrace) from [<8001cf14>] (show_stack+0x10/0x14) [ 44.007432] [<8001cf14>] (show_stack) from [<801ab614>] (dump_stack+0x80/0x90) [ 44.014695] [<801ab614>] (dump_stack) from [<802e4548>] (__skb_checksum_complete+0x6c/0xac) [ 44.023090] [<802e4548>] (__skb_checksum_complete) from [<803a055c>] (ipv6_mc_validate_checksum+0x104/0x178) [ 44.032959] [<803a055c>] (ipv6_mc_validate_checksum) from [<802e111c>] (skb_checksum_trimmed+0x130/0x188) [ 44.042565] [<802e111c>] (skb_checksum_trimmed) from [<803a06e8>] (ipv6_mc_check_mld+0x118/0x338) [ 44.051501] [<803a06e8>] (ipv6_mc_check_mld) from [<803b2c98>] (br_multicast_rcv+0x5dc/0xd00) [ 44.060077] [<803b2c98>] (br_multicast_rcv) from [<803aa510>] (br_handle_frame_finish+0xac/0x51c) [...] Fixes: 9afd85c9e455 ("net: Export IGMP/MLD message validation code") Reported-by: Álvaro Fernández Rojas Signed-off-by: Linus Lüssing --- Steinar, can you check whether this fixes the bridge issues you reported on bugzilla #99081? Not quite sure whether it is the same as yours as you do not seem to have any such call traces. I am not super happy with how this patch looks, but there is no "skb_push_rcsum" available and skb_pull_rcsum() seems non-reversible as is. Alternative suggestions always welcome. net/core/skbuff.c | 19 ++++++++++++++++++- 1 file changed, 18 insertions(+), 1 deletion(-) diff --git a/net/core/skbuff.c b/net/core/skbuff.c index 5bf88f5..6c34ef6 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -4076,6 +4076,11 @@ struct sk_buff *skb_checksum_trimmed(struct sk_buff *skb, struct sk_buff *skb_chk; unsigned int offset = skb_transport_offset(skb); __sum16 ret; + int ip_summed; + int csum_valid; + int csum_level; + int csum_bad; + __wsum csum; skb_chk = skb_checksum_maybe_trim(skb, transport_len); if (!skb_chk) @@ -4084,10 +4089,22 @@ struct sk_buff *skb_checksum_trimmed(struct sk_buff *skb, if (!pskb_may_pull(skb_chk, offset)) goto err; - __skb_pull(skb_chk, offset); + ip_summed = skb->ip_summed; + csum_valid = skb->csum_valid; + csum_level = skb->csum_level; + csum_bad = skb->csum_bad; + csum = skb->csum; + + skb_pull_rcsum(skb_chk, offset); ret = skb_chkf(skb_chk); __skb_push(skb_chk, offset); + skb->ip_summed = ip_summed; + skb->csum_valid = csum_valid; + skb->csum_level = csum_level; + skb->csum_bad = csum_bad; + skb->csum = csum; + if (ret) goto err; -- 1.7.10.4