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=-3.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no 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 71AD4C4360D for ; Sun, 22 Sep 2019 02:08:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 39E0620C01 for ; Sun, 22 Sep 2019 02:08:10 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=netronome-com.20150623.gappssmtp.com header.i=@netronome-com.20150623.gappssmtp.com header.b="RnTt5UC5" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727103AbfIVCIF (ORCPT ); Sat, 21 Sep 2019 22:08:05 -0400 Received: from mail-pf1-f195.google.com ([209.85.210.195]:40933 "EHLO mail-pf1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727050AbfIVCIE (ORCPT ); Sat, 21 Sep 2019 22:08:04 -0400 Received: by mail-pf1-f195.google.com with SMTP id x127so6915066pfb.7 for ; Sat, 21 Sep 2019 19:08:04 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=netronome-com.20150623.gappssmtp.com; s=20150623; h=date:from:to:cc:subject:message-id:in-reply-to:references :organization:mime-version:content-transfer-encoding; bh=Kvb66r57EbPQuEiewVEGLwLX8v0Dn7y42rkkDZUtJHM=; b=RnTt5UC5Rcofn9wYV3uTNd+zxkWyoijWFwK/pVRO8CYuLNRzMjVsEBDJGiB8cNdmKZ WJcsCdQ9TNStBktqDvN/MCvvX+w6NItqK5UhlRld475uDyRlKcgaMbvcR7XLtULNbehY GGcRI4HqwVhbB7jxlREzydaIVTVJrTQegRBpP2vfvU7ok2D2J1uhDmBgv+m+MTcWuoo7 hXWgF57qmdR4Onku2r8pGVyWAuwgURElbRThys6GTw9tXi7i5ONNnqWB4dyjcYRDBMYS OQxUnkkNHPKoMAExRlxiQRnHAt73JyQJKNFNO0BJYzaZlXNCTmKrk/jwvO4rJL57omqD TYfA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:in-reply-to :references:organization:mime-version:content-transfer-encoding; bh=Kvb66r57EbPQuEiewVEGLwLX8v0Dn7y42rkkDZUtJHM=; b=SQRBr55Ju79QbcLiT2OS30mFzFhLkZZ4whucVGq2mUj94DUbAv/yHMikhouxhDHyoE d7JyHZ4DuowxMJXahA5ASggLgMS9f980jOZ8zMlow0tn9KVmS9DVJduxBzJliFqRXJz4 e2TdU+PPij9ZIn/wt5idEJDr1BMv6P4eP2gKlF92MihQzg4xLgV8p72Qi/NgLNaKQcwS 1V9ow23ysgX33PPTeWK5OWGATZB2SzGoE3LfePpJE2NcxkZGMLCIC5mBYlFRnnMdeSmp 5WP6s1UZvuI1nEI6U+2P3/THy+URg5sDbP14trRHX4Ac3atYdwcgeeQItyGPYwNqCfgw zlGw== X-Gm-Message-State: APjAAAVLd6PNZgm97ZRLJXFmdDPBfiOGyZjaE73uOANoa/znG/qAGc1r 1rFGdzBn+7B+WJq30Nt+gC92Xw== X-Google-Smtp-Source: APXvYqz4xtGA7N/n0ha/z2AbiyyhCvU/mMuFmOOTbWqndkyKsDJX/n2NKU9RD6QCS1/9dZ1CZReoHw== X-Received: by 2002:a62:e917:: with SMTP id j23mr11164022pfh.50.1569118084076; Sat, 21 Sep 2019 19:08:04 -0700 (PDT) Received: from cakuba.netronome.com (c-73-202-202-92.hsd1.ca.comcast.net. [73.202.202.92]) by smtp.gmail.com with ESMTPSA id 192sm2075279pfb.110.2019.09.21.19.08.03 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 21 Sep 2019 19:08:03 -0700 (PDT) Date: Sat, 21 Sep 2019 19:08:00 -0700 From: Jakub Kicinski To: Cong Wang , Eric Dumazet Cc: Eric Dumazet , "David S . Miller" , netdev , syzbot , Vlad Buslov , Jiri Pirko Subject: Re: [PATCH net] net: sched: fix possible crash in tcf_action_destroy() Message-ID: <20190921190800.3f19fe23@cakuba.netronome.com> In-Reply-To: References: <20190918195704.218413-1-edumazet@google.com> Organization: Netronome Systems, Ltd. MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Wed, 18 Sep 2019 14:37:21 -0700, Cong Wang wrote: > On Wed, Sep 18, 2019 at 12:57 PM 'Eric Dumazet' via syzkaller > wrote: > > > > If the allocation done in tcf_exts_init() failed, > > we end up with a NULL pointer in exts->actions. > ... > > diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c > > index efd3cfb80a2ad775dc8ab3c4900bd73d52c7aaad..9aef93300f1c11791acbb9262dfe77996872eafe 100644 > > --- a/net/sched/cls_api.c > > +++ b/net/sched/cls_api.c > > @@ -3027,8 +3027,10 @@ static int tc_dump_chain(struct sk_buff *skb, struct netlink_callback *cb) > > void tcf_exts_destroy(struct tcf_exts *exts) > > { > > #ifdef CONFIG_NET_CLS_ACT > > - tcf_action_destroy(exts->actions, TCA_ACT_UNBIND); > > - kfree(exts->actions); > > + if (exts->actions) { > > I think it is _slightly_ better to check exts->nr_actions!=0 here, > as it would help exts->actions!=NULL&& exts->nr_actions==0 > cases too. > > What do you think? Alternatively, since tcf_exts_destroy() now takes NULL, and so obviously does kfree() - perhaps tcf_action_destroy() should return early if actions are NULL?