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=-2.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT 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 8FAF4C65C20 for ; Mon, 8 Oct 2018 14:59:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 57C042086D for ; Mon, 8 Oct 2018 14:59:57 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="KUlvSU0R" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 57C042086D Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726668AbeJHWMD (ORCPT ); Mon, 8 Oct 2018 18:12:03 -0400 Received: from mail-pl1-f193.google.com ([209.85.214.193]:43192 "EHLO mail-pl1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726379AbeJHWMD (ORCPT ); Mon, 8 Oct 2018 18:12:03 -0400 Received: by mail-pl1-f193.google.com with SMTP id 30-v6so10205785plb.10 for ; Mon, 08 Oct 2018 07:59:55 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:date:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=GWoveWWGGwUZeu4tZ41IH6sdZzafw2X+fl1rxLbRXKo=; b=KUlvSU0R/aSmap0aRZhsImI9svhbbzq1BNI1pP+5tg8d5yc937yM6ugGa347qTHcRh RhSqhDtB3410JM5620/AaB4SIpE5b0sPC8TEUvlk5sMvTNcmhFcctSlm314u7zly+hrp XF1WXD00ige247hW9OMUh8A4pkdMZnUTPewqIzJdGd68Jc76cbUpQy0HjO0HpUuNCqjs Z2lrC95/w71j87TMBlKW0Froed0acfXJ4FHzB+VGj9psu1RE14hzbL/GZq7NmfuYkLTe GXOOeTEegUCm/x1P8H+yuLv9DNDbKRYZs155SP60cQfyuHaW/C6qWjFfAf3xy/T0iK35 bfdg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:date:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=GWoveWWGGwUZeu4tZ41IH6sdZzafw2X+fl1rxLbRXKo=; b=ILB++tkZ0lZ4HpqoMh+Mrz821286y9SFnOOopg1im96xO0U1RDOqmbgg9c/ysT9lNb Ts28VJc9NTPaXeK80g3ZtIifSAzpLuqrpLcwLBenN3Svj/3yOPx50H13hfaPF9MXT/jm huJQewPfF/l+z2s5B6zYwhp5H8ayS2rNTj01l1HO4/3KbFu1eQ0Fjxf0Gcv+00fxEk5B 3vkYQBjAziZ+tWgXEnOK/50KIfAMt6pdk5n2kwztX75N7LH3CEpeM6F6vTnBN2QOS2da 9xF6G+VEyPYpUjcBUhPVE4uMBgcbHUTP3ECzFlUCsidgvNJ1IJl3R+RUc70jea1tF5j/ BSZA== X-Gm-Message-State: ABuFfogqADNk0zyFfLY4qX/TTpNvLja420+d6iOE4Y9ftYPGwzoaZLiE e0x3Nw7KVcMyy5zu48gBlpw= X-Google-Smtp-Source: ACcGV6302qonD8yM3XdOGq8+4A9Xsg4JrpcWUERJZy7taluS+bXnBNhFFWvVEY8QUeEMwkiKEsQ5cg== X-Received: by 2002:a17:902:24b:: with SMTP id 69-v6mr10290315plc.280.1539010794385; Mon, 08 Oct 2018 07:59:54 -0700 (PDT) Received: from localhost ([121.137.63.184]) by smtp.gmail.com with ESMTPSA id p62-v6sm28659104pfp.111.2018.10.08.07.59.52 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Mon, 08 Oct 2018 07:59:53 -0700 (PDT) From: Sergey Senozhatsky X-Google-Original-From: Sergey Senozhatsky Date: Mon, 8 Oct 2018 23:59:50 +0900 To: Petr Mladek Cc: zhe.he@windriver.com, sergey.senozhatsky@gmail.com, rostedt@goodmis.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v5 4/4] printk: Give error on attempt to set log buffer length to over 4G Message-ID: <20181008145950.GA1473@tigerII.localdomain> References: <1538239553-81805-1-git-send-email-zhe.he@windriver.com> <1538239553-81805-4-git-send-email-zhe.he@windriver.com> <20181008135916.gg4kkmoki5bgtco5@pathway.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181008135916.gg4kkmoki5bgtco5@pathway.suse.cz> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On (10/08/18 15:59), Petr Mladek wrote: > I tried this patch with log_buf_len=5G. The kernel did not crash > but dmesg shown some mess. There are several 32-bit variables > to store the size, for example: > > static u32 log_buf_len = __LOG_BUF_LEN; > u32 log_buf_len_get(void) > static u32 log_first_idx; > static u32 log_next_idx; > > I guess that the code somewhere does not detect an overflows > correctly. > > I am not motivated enought to add support for such huge message > buffer. Therefore I suggest to limit it to 32G for now. Yeah, I think we gonna have problems even with a 4G logbuf and a 32-bit user-space doing syslog(int len). I agree on the "not motivated enough" part ;) -ss