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=-5.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,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 BBE5CC43382 for ; Tue, 25 Sep 2018 13:31:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 730D7214AB for ; Tue, 25 Sep 2018 13:31:51 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="X/ps8iRr" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 730D7214AB 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 S1729252AbeIYTjX (ORCPT ); Tue, 25 Sep 2018 15:39:23 -0400 Received: from mail-wr1-f68.google.com ([209.85.221.68]:46434 "EHLO mail-wr1-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729152AbeIYTjX (ORCPT ); Tue, 25 Sep 2018 15:39:23 -0400 Received: by mail-wr1-f68.google.com with SMTP id z3-v6so11552902wrr.13 for ; Tue, 25 Sep 2018 06:31:48 -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=tKkpyHDNFbJ7ClbAahRXzw/RkiZ4V/XPfMwdY67lOUM=; b=X/ps8iRrdTCpQcVvuhiXuOWdjdtrgzAUOwwKUB0GEEvEXI6xNj1Yj3PdrQhF2xXObX rmO+UjxTCXlX5IWQzMm1t2WEH9fDr8cXlWaYg2V/X/V4bce3VBS2cu0E+7BUKlzcjlC0 7JJ/LaDygqvtS3aboo0VZ5Qrtm5TAfmJe307HhjWG9z8COkllrmDr/2/K9xPqkU2l6sj lvyoYu9tUVOvgrAig9QhMTTimTrvXQzKqmy9Y20MOSGOXUaLBFDP8cBxUqORJUUiYLeF cWkRGxNhowx/4ia4b9DWKn3jkU1j5UcmFVHAnzX4TxeEutld87aW5w/b27QARxh5CHYo 5UQw== 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=tKkpyHDNFbJ7ClbAahRXzw/RkiZ4V/XPfMwdY67lOUM=; b=LF4/6cd3AJtjwq8XtZs3UNefOTri7V3V70ju85Q0yjdZRJ5mq6udd27dcDoYrPm1tf L0T92LTe0HPlUOCHG08yWkpfbqWyWSkYoFKIkHq2tm4Et3cnduVexcex38SM3Yj4P7n7 raXtJmkNZt7CwBP6+S0bPjoquBqRoKPRPTJ0lffgH5ss7KfSxRKzQxqZyhmFTmWrRp7K 3RMi6PxAK2VqejsKGWsro3BGnXohtD9m1kh048yQ/EBtIi9mtyTCQO1yAc6ZhTW3M/Uc QFaOb9u7JmEHKJICylRQwICDG++mNg0C0Mdq/mUEN1ib330TI9msoVzw4saP4w41ZNsL gALw== X-Gm-Message-State: ABuFfog4v1M9buFiApxnmOR6rNTKg+nxhCiis97V94pdr9KtEUGc/8gy 8XnChNhLOIyEXTKcZ62KCEo= X-Google-Smtp-Source: ACcGV61HcX/5GpjUEzvj31XVmMre+EVu40G/pYCzfpXFz9HKXSwO1P7tiX6Nq4CFTbEEc6vaD0RzDQ== X-Received: by 2002:a5d:6586:: with SMTP id q6-v6mr1032762wru.141.1537882307669; Tue, 25 Sep 2018 06:31:47 -0700 (PDT) Received: from localhost ([178.121.95.75]) by smtp.gmail.com with ESMTPSA id l40-v6sm441752wre.38.2018.09.25.06.31.46 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Tue, 25 Sep 2018 06:31:46 -0700 (PDT) From: Sergey Senozhatsky X-Google-Original-From: Sergey Senozhatsky Date: Tue, 25 Sep 2018 22:31:43 +0900 To: Petr Mladek Cc: Sergey Senozhatsky , Steven Rostedt , He Zhe , Sergey Senozhatsky , linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 1/2] printk: Fix panic caused by passing log_buf_len to command line Message-ID: <20180925133143.GB601@tigerII.localdomain> References: <1537291068-443145-1-git-send-email-zhe.he@windriver.com> <20180919015030.GA423@jagdpanzerIV> <6c354803-5341-7237-9ee3-7882252c7483@windriver.com> <20180919023932.GA14090@jagdpanzerIV> <20180918224312.6e9aef50@vmware.local.home> <1545bc85-b64a-4b45-d40f-79567ac621dc@windriver.com> <20180920123056.27b2cf18@gandalf.local.home> <20180921073753.mqayzofcofpmhiyu@pathway.suse.cz> <20180925120135.GB523@tigerII.localdomain> <20180925122300.qq5w4skwmxbzi6sy@pathway.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180925122300.qq5w4skwmxbzi6sy@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 (09/25/18 14:23), Petr Mladek wrote: > The 32GB was mentioned as an example one year ego. This is not enough > for a new syscall from my point of view. I agree. I didn't think of syslog(); was merely thinking about logbuf and flushing it to the consoles. syslog() stuff is a bit complex. We sort of don't expect user space to allocate 64G to read all log_buf messages, do we. I'm wondering if we can do something like this --- diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c index cf275f4d7912..1b48b61da8fe 100644 --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -1110,9 +1110,15 @@ static void __init log_buf_len_update(unsigned size) /* save requested log_buf_len since it's too early to process it */ static int __init log_buf_len_setup(char *str) { - unsigned size = memparse(str, &str); + u64 size = memparse(str, &str); - log_buf_len_update(size); + if (size > UINT_MAX) { + size = UINT_MAX; + pr_err("log_buf over 4G is not supported. " + "Please contact printk maintainers.\n"); + } + + log_buf_len_update((unsigned int)size); return 0; } --- So we could know that "the day has come". -ss