From patchwork Mon Jul 29 08:00:18 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jia-Ju Bai X-Patchwork-Id: 1138234 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming-netdev@ozlabs.org Delivered-To: patchwork-incoming-netdev@ozlabs.org Authentication-Results: ozlabs.org; spf=none (mailfrom) smtp.mailfrom=vger.kernel.org (client-ip=209.132.180.67; helo=vger.kernel.org; envelope-from=netdev-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=gmail.com header.i=@gmail.com header.b="IL7E+lWA"; dkim-atps=neutral Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 45xsYt6br9z9sML for ; Mon, 29 Jul 2019 18:00:34 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727324AbfG2IAa (ORCPT ); Mon, 29 Jul 2019 04:00:30 -0400 Received: from mail-pf1-f196.google.com ([209.85.210.196]:40587 "EHLO mail-pf1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726586AbfG2IAa (ORCPT ); Mon, 29 Jul 2019 04:00:30 -0400 Received: by mail-pf1-f196.google.com with SMTP id p184so27589366pfp.7; Mon, 29 Jul 2019 01:00:30 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id; bh=sHreTI6pjMjpSS3l9XfOzmIgje94ZwckoRy4s15t6gc=; b=IL7E+lWAmJRAOYrpHdkkAku6XU17qS8ac815x+cn7Pi3NZuvBbyEhBRTllzGkFaM17 zgxZa4xgDCgCXCa6pLRvwTb0XRHIRfURmP+Y1rRCTZ/NPMhMv8pi+WsXkpa7Kw66ZJR1 Y/2JWEAU8qGlBeGPXBckBROIe2lUCe+UG7ZFQ8QbH7Y61hT/9UlZ6ae17ng01nVm47BM MkV2J1ca/Ge5hds5Cu2O/SBFsinTCog4MCj3Yt4JldhUMLqQp8kjMinwr3dBI/Xrx4xJ cwfO45AWPHZV1Tx2fc7LU81EheGEYzZUYdfxOkR13frk1ik+oC1f8H+ReSEKMLPYLM7M qQPA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id; bh=sHreTI6pjMjpSS3l9XfOzmIgje94ZwckoRy4s15t6gc=; b=Fnl8jqYuLXIeijFrO+NkdyM/ri7Gzroa5ziAWCGzYa2cWUqfbNcfShYZxR6S6MZ0WM 5JJuC3A2+eJab3GWrg8a4Q6TCC3P1FQUmRsGcLJ5L5+yBTUBdY7/jwYh941T+BlNy0Sb sAi3nUTchN+s7aUGXd10/Xfbt1+N0YfTs4aqh6WQ/sxKt7onx3C7nNBNuMQIBQyhODHh DInUUrLWy6pcpNu6fofXkQDPxVw8jdk/e8+3YfSPqchh64ZYz5z+gGV7WmT9b0bIjcuT hCWNdzltgRzQD/kt8jKXf71cXuEUr4M9RYPOTXj0M7Y+6H4+Ap7u3t8yX97xmLP1ecRG GGlA== X-Gm-Message-State: APjAAAWKbSo8n3VYQKuYZBuEhzaLYOkVBJNCg0j5xJ1gH+dopU7Hnnm9 E6REclFn6pr9tW1tMWNnWpVZVDyV4U8= X-Google-Smtp-Source: APXvYqwtYEnuKAS9Muhpr3xUIRtlZkMmMYnvmpbRAL8N7K0KvFCMNFzu4hQ3MN5AF1/t9Rg/PbAbdg== X-Received: by 2002:a17:90a:c70c:: with SMTP id o12mr85447831pjt.62.1564387229826; Mon, 29 Jul 2019 01:00:29 -0700 (PDT) Received: from oslab.tsinghua.edu.cn ([2402:f000:4:72:808::3ca]) by smtp.gmail.com with ESMTPSA id p15sm58050661pjf.27.2019.07.29.01.00.27 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 29 Jul 2019 01:00:29 -0700 (PDT) From: Jia-Ju Bai To: jhs@mojatatu.com, xiyou.wangcong@gmail.com, jiri@resnulli.us, davem@davemloft.net Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Jia-Ju Bai Subject: [PATCH v2] net: sched: Fix a possible null-pointer dereference in dequeue_func() Date: Mon, 29 Jul 2019 16:00:18 +0800 Message-Id: <20190729080018.28678-1-baijiaju1990@gmail.com> X-Mailer: git-send-email 2.17.0 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org In dequeue_func(), there is an if statement on line 74 to check whether skb is NULL: if (skb) When skb is NULL, it is used on line 77: prefetch(&skb->end); Thus, a possible null-pointer dereference may occur. To fix this bug, skb->end is used when skb is not NULL. This bug is found by a static analysis tool STCheck written by us. Fixes: 79bdc4c862af ("codel: generalize the implementation") Signed-off-by: Jia-Ju Bai Reviewed-by: Jiri Pirko --- v2: * Add a fix tag. Thank Jiri Pirko for helpful advice. --- net/sched/sch_codel.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/net/sched/sch_codel.c b/net/sched/sch_codel.c index 25ef172c23df..30169b3adbbb 100644 --- a/net/sched/sch_codel.c +++ b/net/sched/sch_codel.c @@ -71,10 +71,10 @@ static struct sk_buff *dequeue_func(struct codel_vars *vars, void *ctx) struct Qdisc *sch = ctx; struct sk_buff *skb = __qdisc_dequeue_head(&sch->q); - if (skb) + if (skb) { sch->qstats.backlog -= qdisc_pkt_len(skb); - - prefetch(&skb->end); /* we'll need skb_shinfo() */ + prefetch(&skb->end); /* we'll need skb_shinfo() */ + } return skb; }