From patchwork Mon Jul 29 02:21:57 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: 1138097 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="NDckJD4L"; dkim-atps=neutral Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 45xk3S0Mv9z9sML for ; Mon, 29 Jul 2019 12:22:12 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726470AbfG2CWF (ORCPT ); Sun, 28 Jul 2019 22:22:05 -0400 Received: from mail-pg1-f195.google.com ([209.85.215.195]:37853 "EHLO mail-pg1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726251AbfG2CWE (ORCPT ); Sun, 28 Jul 2019 22:22:04 -0400 Received: by mail-pg1-f195.google.com with SMTP id i70so16664713pgd.4; Sun, 28 Jul 2019 19:22:04 -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=7fp1YuLIkMp6V8LF5r3sZVLgOMYUpY55IUl5NCyG7hQ=; b=NDckJD4LK99YxCkG/Uove+eO+w0elZ6wg+NR79uzg5bvZfri5Opl3sEsl2Bkb2yBmV 0N3VNYxCruJ8jiyuya3Hrb2dsklL5xlB2t84gVkQYLy9urKgwj2wDLgtMp/KeZWYbN6Q i2ZGiaAf7R7iklB3W8KDkeo+fhhteBW95MKj0Vl/CZAd0d/LLdRxv9gCKfEV8sObclw4 3IQAVmsHDEHyGQlxWKvyGQ0TZkBmSVLNcYRDE40RGzdk3e2DTAHTzb0hUcRVEBdL3Br8 VQxG0Y8YqoGEwCS8MAABUrGvWsWSR/In0XlEXA6tnCeG2rAioJ4uimRuX1xHBdRd4y9p +KOQ== 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=7fp1YuLIkMp6V8LF5r3sZVLgOMYUpY55IUl5NCyG7hQ=; b=LUsuLeaCz2wOOO5NnXlCGnw7q4ksK7vFVjNrSArcv+2d4u7lzYG5bwyn1SR1Wv7uNe s5NFqUEzPYTpn8Ec7ZnrxZyMeuyd45tMXJK36IzuG+wCJohUMP97dhdt73UB0+WRfwL4 5XobdpnpOYZqR/N2n0oQBA3QRF+81CUyN5KYinDrWeQvjzp8J4qQC9ZRWqCE9rE0o7vS Wtif62Q92BcNYqNlrELTZ8lfbzChLqk1y97FTsOjrZBLiTEvqTj7tndg1T64stARMM0N 0z/9S3o1v5b7hyREKIPswDtsR7vWxwsqn5sJObbrMZTv1isLLBwKW9lIH8pBTTFQMobJ vjHw== X-Gm-Message-State: APjAAAXZmE5IWpzFs7HSUk+xk6hlaeb7UrljYwlVcPURsO+yMmzFRvzq 1C/rzF+D9q0ffEEodUz6scE= X-Google-Smtp-Source: APXvYqzRaqTartOBdQBYeocDw9EcrmOmZjGSJiZ5Hfc6SJQaHiSUImp3RF/PBFkzFSmfB7s0CczkgQ== X-Received: by 2002:a63:d04e:: with SMTP id s14mr97287640pgi.189.1564366924059; Sun, 28 Jul 2019 19:22:04 -0700 (PDT) Received: from oslab.tsinghua.edu.cn ([2402:f000:4:72:808::3ca]) by smtp.gmail.com with ESMTPSA id j128sm56150318pfg.28.2019.07.28.19.22.02 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sun, 28 Jul 2019 19:22:03 -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] net: sched: Fix a possible null-pointer dereference in dequeue_func() Date: Mon, 29 Jul 2019 10:21:57 +0800 Message-Id: <20190729022157.18090-1-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. Signed-off-by: Jia-Ju Bai --- 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; }