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=-9.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,USER_AGENT_GIT autolearn=ham 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 11186C2BC61 for ; Tue, 30 Oct 2018 13:30:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C984320838 for ; Tue, 30 Oct 2018 13:30:57 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="ObSqh7zb" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C984320838 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729068AbeJ3WYY (ORCPT ); Tue, 30 Oct 2018 18:24:24 -0400 Received: from mail.kernel.org ([198.145.29.99]:54284 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727774AbeJ3WYX (ORCPT ); Tue, 30 Oct 2018 18:24:23 -0400 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id EE98B208A3; Tue, 30 Oct 2018 13:30:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1540906254; bh=MYo69oEdK4CE/XTh61y242H+81KDl3+qHbgTRp0JHmA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ObSqh7zb56znyiYT31IZ+TSE4l6YDhUBMfgK3Qo23Gm6BsFbgepSEc5MtdoRuVl7J 8quS4nLaHUV1UbNnd9j5e2EwBqj5+USyN+mqXoXLdrEKpQlihxL/QdYVhdsu8fGzaT Y41CNM94RuGmTk52U+PNGlFBRo3oFXhU5j9r3hY8= From: Sasha Levin To: stable@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Dimitris Michailidis , "David S . Miller" , Sasha Levin Subject: [PATCH AUTOSEL 4.9 12/13] net: fix pskb_trim_rcsum_slow() with odd trim offset Date: Tue, 30 Oct 2018 09:29:22 -0400 Message-Id: <20181030132923.218124-12-sashal@kernel.org> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20181030132923.218124-1-sashal@kernel.org> References: <20181030132923.218124-1-sashal@kernel.org> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Dimitris Michailidis [ Upstream commit d55bef5059dd057bd077155375c581b49d25be7e ] We've been getting checksum errors involving small UDP packets, usually 59B packets with 1 extra non-zero padding byte. netdev_rx_csum_fault() has been complaining that HW is providing bad checksums. Turns out the problem is in pskb_trim_rcsum_slow(), introduced in commit 88078d98d1bb ("net: pskb_trim_rcsum() and CHECKSUM_COMPLETE are friends"). The source of the problem is that when the bytes we are trimming start at an odd address, as in the case of the 1 padding byte above, skb_checksum() returns a byte-swapped value. We cannot just combine this with skb->csum using csum_sub(). We need to use csum_block_sub() here that takes into account the parity of the start address and handles the swapping. Matches existing code in __skb_postpull_rcsum() and esp_remove_trailer(). Fixes: 88078d98d1bb ("net: pskb_trim_rcsum() and CHECKSUM_COMPLETE are friends") Signed-off-by: Dimitris Michailidis Reviewed-by: Eric Dumazet Signed-off-by: David S. Miller Signed-off-by: Sasha Levin --- net/core/skbuff.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/net/core/skbuff.c b/net/core/skbuff.c index 038ec74fa131..68ecb7d71c2b 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -1585,8 +1585,9 @@ int pskb_trim_rcsum_slow(struct sk_buff *skb, unsigned int len) if (skb->ip_summed == CHECKSUM_COMPLETE) { int delta = skb->len - len; - skb->csum = csum_sub(skb->csum, - skb_checksum(skb, len, delta, 0)); + skb->csum = csum_block_sub(skb->csum, + skb_checksum(skb, len, delta, 0), + len); } return __pskb_trim(skb, len); } -- 2.17.1