From mboxrd@z Thu Jan 1 00:00:00 1970 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754676AbdBET2X (ORCPT + 2 others); Sun, 5 Feb 2017 14:28:23 -0500 Received: from wtarreau.pck.nerim.net ([62.212.114.60]:28489 "EHLO 1wt.eu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754658AbdBET2V (ORCPT ); Sun, 5 Feb 2017 14:28:21 -0500 From: Willy Tarreau To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, linux@roeck-us.net Cc: Eric Dumazet , =?UTF-8?q?Maciej=20=C5=BBenczykowski?= , Willem de Bruijn , "David S . Miller" , Willy Tarreau Subject: [PATCH 3.10 260/319] net: mangle zero checksum in skb_checksum_help() Date: Sun, 5 Feb 2017 20:21:22 +0100 Message-Id: <1486322541-8206-161-git-send-email-w@1wt.eu> X-Mailer: git-send-email 2.8.0.rc2.1.gbe9624a In-Reply-To: <1486322541-8206-1-git-send-email-w@1wt.eu> References: <1486322541-8206-1-git-send-email-w@1wt.eu> MIME-Version: 1.0 Content-Type: text/plain; charset=latin1 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Return-Path: From: Eric Dumazet commit 4f2e4ad56a65f3b7d64c258e373cb71e8d2499f4 upstream. Sending zero checksum is ok for TCP, but not for UDP. UDPv6 receiver should by default drop a frame with a 0 checksum, and UDPv4 would not verify the checksum and might accept a corrupted packet. Simply replace such checksum by 0xffff, regardless of transport. This error was caught on SIT tunnels, but seems generic. Signed-off-by: Eric Dumazet Cc: Maciej Żenczykowski Cc: Willem de Bruijn Acked-by: Maciej Żenczykowski Signed-off-by: David S. Miller Signed-off-by: Willy Tarreau --- net/core/dev.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/core/dev.c b/net/core/dev.c index 408f6ee..6494918 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -2234,7 +2234,7 @@ int skb_checksum_help(struct sk_buff *skb) goto out; } - *(__sum16 *)(skb->data + offset) = csum_fold(csum); + *(__sum16 *)(skb->data + offset) = csum_fold(csum) ?: CSUM_MANGLED_0; out_set_summed: skb->ip_summed = CHECKSUM_NONE; out: -- 2.8.0.rc2.1.gbe9624a