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=-8.6 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,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 C3C28C4727E for ; Wed, 30 Sep 2020 13:30:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 681B62075F for ; Wed, 30 Sep 2020 13:30:02 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=suse.com header.i=@suse.com header.b="ut/k+j0q" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730276AbgI3NaB (ORCPT ); Wed, 30 Sep 2020 09:30:01 -0400 Received: from mx2.suse.de ([195.135.220.15]:42116 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728232AbgI3NaA (ORCPT ); Wed, 30 Sep 2020 09:30:00 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1601472599; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=0aGG+CtqPGJmiOFOGGIQ/c+ZReYi/AbBk1CjcE4dLTQ=; b=ut/k+j0qSZgIEIYILuBPWBwhFCjWK/DChunNrFI6SL8nJwwKsf1UPFUYr4c9AFZP0Y7WY4 K1fXalm3sATwee+57R5egng0bNKov20kRqYps7s71drrHH5IIShCA0QeEnYy/Xa7Nj6Cl5 Y4cSYmSkqWiLDS2c3qr3QC76ghVP9a4= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 9330FABCC; Wed, 30 Sep 2020 13:29:59 +0000 (UTC) Date: Wed, 30 Sep 2020 15:29:58 +0200 From: Petr Mladek To: John Ogness Cc: Sergey Senozhatsky , Sergey Senozhatsky , Steven Rostedt , Linus Torvalds , Greg Kroah-Hartman , Thomas Gleixner , Marek Szyprowski , linux-kernel@vger.kernel.org Subject: Re: [PATCH next v2 1/2] printk: avoid and/or handle record truncation Message-ID: <20200930132958.GF29288@alley> References: <20200930090134.8723-1-john.ogness@linutronix.de> <20200930090134.8723-2-john.ogness@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200930090134.8723-2-john.ogness@linutronix.de> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed 2020-09-30 11:07:33, John Ogness wrote: > If a reader provides a buffer that is smaller than the message text, > the @text_len field of @info will have a value larger than the buffer > size. If readers blindly read @text_len bytes of data without > checking the size, they will read beyond their buffer. > > Add this check to record_print_text() to properly recognize when such > truncation has occurred. > > Add a maximum size argument to the ringbuffer function to extend > records so that records can not be created that are larger than the > buffer size of readers. > > When extending records (LOG_CONT), do not extend records beyond > LOG_LINE_MAX since that is the maximum size available in the buffers > used by consoles and syslog. > > Fixes: f5f022e53b87 ("printk: reimplement log_cont using record extension") > Signed-off-by: John Ogness > Reported-by: Marek Szyprowski Reviewed-by: Petr Mladek Best Regards, Petr