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=-0.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 C0E89C48BD5 for ; Tue, 25 Jun 2019 11:25:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 99AE0215EA for ; Tue, 25 Jun 2019 11:25:05 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=mojatatu-com.20150623.gappssmtp.com header.i=@mojatatu-com.20150623.gappssmtp.com header.b="iBj3bF+K" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730263AbfFYLZB (ORCPT ); Tue, 25 Jun 2019 07:25:01 -0400 Received: from mail-qk1-f195.google.com ([209.85.222.195]:45644 "EHLO mail-qk1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726702AbfFYLYk (ORCPT ); Tue, 25 Jun 2019 07:24:40 -0400 Received: by mail-qk1-f195.google.com with SMTP id s22so12203113qkj.12 for ; Tue, 25 Jun 2019 04:24:39 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=mojatatu-com.20150623.gappssmtp.com; s=20150623; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=Q67GX7ogcyNGHOVFbGOWKsdPM61okAiYlmyIGQtFKqI=; b=iBj3bF+KsBwev9IcArvxqrzoQjGeBjdhXnBOgDq8JX3sYlyLYLDkF83tYYcDAyP5R7 tWe8KMKoU3TE1zPz9Yg883Fpv8bCHNXN/sadcNZziLMV2uG8YTN+eWR8MShqY/nvj+8F /eDvdwlkQXRVHQSjHijDrhYCge3g5rM977DYG+hKYfek41rRBT2EiafV0mxUuM8Ey6L5 3J9Bsv+QNn5gBm8V+8bbjmdG5o0+QjMEYwpIUFn+Mos2FmblP8XwfRg0L8BZJIBVhBZk zhGsgn8sGbvIbgf+2wzG7SVjI7AgZbHxe4h5QHIYc8iCgKl8VIafsWwy5vufhXb9aiyz /4oQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=Q67GX7ogcyNGHOVFbGOWKsdPM61okAiYlmyIGQtFKqI=; b=sKmpQqdnkFCLdYXHw+FAc7dIE1z9gMaKo7zTWc0SyFFxRikbpQCfXeCnsyERS3F0+P QQjtyr7M/Re61VnenTTBfl+hg/XJO2Y2Rp15nTaHPtblpx7iW0y1f0QiGiQzXuq6I0Up Lg09cChCtNQHmNIl4eG5dvd8O50/j17NcCu9FGm640WNhSEe/gVzOto6ODflUfm3KSSJ tZoHj0HFXw0+tDotybGkuQRi/2PvL2XWWIujwPb2Zgs1VzKf9jdVISrlEYo28qAUUfF8 Oay8+UlIkAgnKwN9HxdcxCIECSh8hh/P1FPFmvpMUiWGZ2CSNAa3jADo9ANNp8XLDcpt 4ZoQ== X-Gm-Message-State: APjAAAW0KHsJTNnCCtAbmpyCg43I6DiM3boTT2/cAOA/pof0aur83/5+ Lued0A9Bog3Iab7opJjrk9pagQ== X-Google-Smtp-Source: APXvYqzEaMHhL1QE5xJCqAQ+MI97DkXvZF66AOX+XAdOUa4SriFcfuaguT5yBFSvr7aRKpQ3bZH8Fw== X-Received: by 2002:a37:9c16:: with SMTP id f22mr124589476qke.261.1561461879107; Tue, 25 Jun 2019 04:24:39 -0700 (PDT) Received: from [192.168.0.124] (24-212-162-241.cable.teksavvy.com. [24.212.162.241]) by smtp.googlemail.com with ESMTPSA id j79sm8036529qke.112.2019.06.25.04.24.37 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 25 Jun 2019 04:24:38 -0700 (PDT) Subject: Re: [PATCH net-next 2/2] net: sched: protect against stack overflow in TC act_mirred To: John Hurley , Eyal Birger Cc: Linux Netdev List , David Miller , Florian Westphal , Simon Horman , Jakub Kicinski , oss-drivers@netronome.com, shmulik@metanetworks.com References: <1561414416-29732-1-git-send-email-john.hurley@netronome.com> <1561414416-29732-3-git-send-email-john.hurley@netronome.com> <20190625113010.7da5dbcb@jimi> From: Jamal Hadi Salim Message-ID: <4a4f2f81-d87a-2a45-36b9-ac101d937219@mojatatu.com> Date: Tue, 25 Jun 2019 07:24:37 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.2 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On 2019-06-25 5:06 a.m., John Hurley wrote: > On Tue, Jun 25, 2019 at 9:30 AM Eyal Birger wrote: > I'm not sure on the history of why a value of 4 was selected here but > it seems to fall into line with my findings. Back then we could only loop in one direction (as opposed to two right now) - so seeing something twice would have been suspect enough, so 4 seems to be a good number. I still think 4 is a good number. > Is there a hard requirement for >4 recursive calls here? I think this is where testcases help (which then get permanently added in tdc repository). Eyal - if you have a test scenario where this could be demonstrated it would help. cheers, jamal