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=-8.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY, USER_AGENT_SANE_1 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 12DADC3524D for ; Mon, 3 Feb 2020 08:39:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DAD4420661 for ; Mon, 3 Feb 2020 08:39:23 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="p64Dxniz" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727805AbgBCIjW (ORCPT ); Mon, 3 Feb 2020 03:39:22 -0500 Received: from aserp2120.oracle.com ([141.146.126.78]:42356 "EHLO aserp2120.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726082AbgBCIjW (ORCPT ); Mon, 3 Feb 2020 03:39:22 -0500 Received: from pps.filterd (aserp2120.oracle.com [127.0.0.1]) by aserp2120.oracle.com (8.16.0.27/8.16.0.27) with SMTP id 0138c3np067675; Mon, 3 Feb 2020 08:39:08 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=date : from : to : cc : subject : message-id : references : mime-version : content-type : in-reply-to; s=corp-2019-08-05; bh=lh1h0yHtzO5kI/7xMb6UmPUubBBS5DwI9HPKs5tX72Q=; b=p64DxnizsgWHOspKnbq/b5YcvY1r18L37bAHRpY9G0pudaRqmOXnup5CbP3ab4Uz5eul J4SM66Vdf50nWAln7YsxuihXWEskwQB7oE32Saaar2SiKuh7jBVcOCF6f5nl6EWzL50s 6V8lCAvHHonPVNI7MuJoM5ZWjvnPAS2/j/ubQhwdZEqg9x87++sFn2fHa3w/FNGj3q8z TtoVEjJQSdH7ZticzzAHCJjfdvZe1yp5NSQTkjzCb5oIJzaRDma0daDjNZYOMOBQsMzo j6Qr2AjmReh5oKXjg8i9PMdEM7ce5J1cFcl8Ov3eHHz62870UvpJRJgSV2Xf0bdcRd3v Ew== Received: from userp3020.oracle.com (userp3020.oracle.com [156.151.31.79]) by aserp2120.oracle.com with ESMTP id 2xw19q656c-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 03 Feb 2020 08:39:07 +0000 Received: from pps.filterd (userp3020.oracle.com [127.0.0.1]) by userp3020.oracle.com (8.16.0.27/8.16.0.27) with SMTP id 0138YFUB091185; Mon, 3 Feb 2020 08:39:07 GMT Received: from userv0122.oracle.com (userv0122.oracle.com [156.151.31.75]) by userp3020.oracle.com with ESMTP id 2xwkfsrhac-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 03 Feb 2020 08:39:07 +0000 Received: from abhmp0015.oracle.com (abhmp0015.oracle.com [141.146.116.21]) by userv0122.oracle.com (8.14.4/8.14.4) with ESMTP id 0138d35A022392; Mon, 3 Feb 2020 08:39:03 GMT Received: from kadam (/41.210.143.134) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Mon, 03 Feb 2020 00:39:03 -0800 Date: Mon, 3 Feb 2020 11:38:53 +0300 From: Dan Carpenter To: Cong Wang Cc: Jamal Hadi Salim , Jiri Pirko , "David S. Miller" , Jakub Kicinski , Mohit Bhasi , "Mohit P. Tahiliani" , "V. Saicharan" , Gautam Ramakrishnan , Linux Kernel Network Developers , kernel-janitors@vger.kernel.org Subject: Re: [PATCH net] net: sched: prevent a use after free Message-ID: <20200203083853.GH11068@kadam> References: <20200131065647.joonbg3wzcw26x3b@kili.mountain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.9.4 (2018-02-28) X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9519 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=0 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1911140001 definitions=main-2002030069 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9519 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1911140001 definitions=main-2002030069 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Sat, Feb 01, 2020 at 11:38:43AM -0800, Cong Wang wrote: > On Thu, Jan 30, 2020 at 10:57 PM Dan Carpenter wrote: > > > > The code calls kfree_skb(skb); and then re-uses "skb" on the next line. > > Let's re-order these lines to solve the problem. > > > > Fixes: ec97ecf1ebe4 ("net: sched: add Flow Queue PIE packet scheduler") > > Signed-off-by: Dan Carpenter > > --- > > net/sched/sch_fq_pie.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/net/sched/sch_fq_pie.c b/net/sched/sch_fq_pie.c > > index bbd0dea6b6b9..78472e0773e9 100644 > > --- a/net/sched/sch_fq_pie.c > > +++ b/net/sched/sch_fq_pie.c > > @@ -349,9 +349,9 @@ static int fq_pie_change(struct Qdisc *sch, struct nlattr *opt, > > while (sch->q.qlen > sch->limit) { > > struct sk_buff *skb = fq_pie_qdisc_dequeue(sch); > > > > - kfree_skb(skb); > > len_dropped += qdisc_pkt_len(skb); > > num_dropped += 1; > > + kfree_skb(skb); > > Or even better: use rtnl_kfree_skbs(). Why is that better? regards, dan carpenter