From patchwork Thu Aug 13 10:21:07 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andy Whitcroft X-Patchwork-Id: 506918 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 076B114028F for ; Thu, 13 Aug 2015 20:21:37 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752348AbbHMKVL (ORCPT ); Thu, 13 Aug 2015 06:21:11 -0400 Received: from mail-wi0-f175.google.com ([209.85.212.175]:34671 "EHLO mail-wi0-f175.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751714AbbHMKVJ (ORCPT ); Thu, 13 Aug 2015 06:21:09 -0400 Received: by wicne3 with SMTP id ne3so252946923wic.1 for ; Thu, 13 Aug 2015 03:21:08 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:from:to:cc:subject:date:message-id; bh=EiEPy/IBRyAtVuKN9qBfU3juyF4rCdZn1TZ13bvVEvw=; b=ACQ/mjA/TMnAdxJwkIcwJXIsJlk2d+FZFuZ0xcy5H7pXHGSRZNC4rHkwfe7ZPyMyco 0bEXFeFpyhfraYO3aT0DkONJ8TfK0R47HR5R53MhMXHqLmcHaAG4XcUztbzKDycJYtPg EqBAEjJSuz4PCx9t424iGJVJHWUizKdlPUAhtSrhgba2d+mFCKG0FZFi/HyfOOBcpVoq RaOTR9kXu2UDIjZWFHWDyQlulecKUScB0y+A72bJd+sqHtJsHTTUXcWe+yIINMHmiukz ZYtKdw9RzqbicgfpxsLdh0cTRQrZMY5EDpbb4+6RP5P7st/eGtLs1wNRGVZwMUZvulGC BdSQ== X-Gm-Message-State: ALoCoQmEskQ0tRhQiEbzeYug9KSwrsABAZ2rTFT0uadjYcCN8yCDGNZGtCKQD6XJD9mafAZrZyuv X-Received: by 10.180.103.231 with SMTP id fz7mr5185715wib.91.1439461268643; Thu, 13 Aug 2015 03:21:08 -0700 (PDT) Received: from localhost ([149.18.33.207]) by smtp.gmail.com with ESMTPSA id fs8sm2645335wjb.7.2015.08.13.03.21.07 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 13 Aug 2015 03:21:07 -0700 (PDT) From: Andy Whitcroft To: "David S. Miller" , Alexey Kuznetsov , James Morris , Hideaki YOSHIFUJI , Patrick McHardy Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Andy Whitcroft Subject: [PATCH 1/1] ipv4: off-by-one in continuation handling in /proc/net/route Date: Thu, 13 Aug 2015 11:21:07 +0100 Message-Id: <1439461267-10627-1-git-send-email-apw@canonical.com> X-Mailer: git-send-email 2.5.0 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org When generating /proc/net/route we emit a header followed by a line for each route. When a short read is performed we will restart this process based on the open file descriptor. When calculating the start point we fail to take into account that the 0th entry is the header. This leads us to skip the first entry when doing a continuation read. This can be easily seen with the comparison below: while read l; do echo "$l"; done A cat /proc/net/route >B diff -bu A B | grep '^[+-]' On my example machine I have approximatly 10KB of route output. There we see the very first non-title element is lost in the while read case, and an entry around the 8K mark in the cat case: +wlan0 00000000 02021EAC 0003 0 0 400 00000000 0 0 0 -tun1 00C0AC0A 00000000 0001 0 0 950 00C0FFFF 0 0 0 Fix up the off-by-one when reaquiring position on continuation. BugLink: http://bugs.launchpad.net/bugs/1483440 Signed-off-by: Andy Whitcroft Acked-by: Alexander Duyck --- net/ipv4/fib_trie.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) From code inspection I belive this was introduced by the Fixes below, but I have not tested this to confirm. Fixes: 8be33e955cb9 ("ipv4: off-by-one in continuation handling in /proc/net/route") diff --git a/net/ipv4/fib_trie.c b/net/ipv4/fib_trie.c index 37c4bb8..b0c6258 100644 --- a/net/ipv4/fib_trie.c +++ b/net/ipv4/fib_trie.c @@ -2465,7 +2465,7 @@ static struct key_vector *fib_route_get_idx(struct fib_route_iter *iter, key = l->key + 1; iter->pos++; - if (pos-- <= 0) + if (--pos <= 0) break; l = NULL;