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=-9.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable 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 DEA56C432C3 for ; Wed, 27 Nov 2019 21:37:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id AA8072086A for ; Wed, 27 Nov 2019 21:37:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1574890663; bh=7nybk/T84jG+yY80/3VieVPJKJrELADi6/UIcReZYhM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=t8OGFEi9kgSw8a9NR1iDm3AOF5bHFYjRd3jsYuMM375iEGM2VLdQqJrJNgOln3KOQ wGkESE3CIpz2MpwxF89NMhSJkkYbqbWlJW7P18od11vyAapx2rnzf4PAnV6o1qd8Vk NEgXOkZvVu+OTxfWohfjpyPBg2dhd6obrKdRlr4U= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728812AbfK0Uqc (ORCPT ); Wed, 27 Nov 2019 15:46:32 -0500 Received: from mail.kernel.org ([198.145.29.99]:58512 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729887AbfK0Uqc (ORCPT ); Wed, 27 Nov 2019 15:46:32 -0500 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id C73A62158A; Wed, 27 Nov 2019 20:46:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1574887591; bh=7nybk/T84jG+yY80/3VieVPJKJrELADi6/UIcReZYhM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=z7xlFXOiCJFXNVZjMiyXmJgR/pKVfNFPDvIe9J2DyShO3pUJa0gTXZhwAebC4qHa7 v+tySv80nIwmlIu9ou7n6F6C8WHGkE6uMyrXM3rfwIV6H5z7Ma3OssUQ8iRg/DqqaN fe+tDiC4bqFADiyqh1hRCpxKZtZLoCYqa6jSz+Os= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org, Steven Rostedt Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Sergey Senozhatsky , Sergey Senozhatsky , Petr Mladek , Sasha Levin Subject: [PATCH 4.14 019/211] printk: fix integer overflow in setup_log_buf() Date: Wed, 27 Nov 2019 21:29:12 +0100 Message-Id: <20191127203052.837882082@linuxfoundation.org> X-Mailer: git-send-email 2.24.0 In-Reply-To: <20191127203049.431810767@linuxfoundation.org> References: <20191127203049.431810767@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Sergey Senozhatsky [ Upstream commit d2130e82e9454304e9b91ba9da551b5989af8c27 ] The way we calculate logbuf free space percentage overflows signed integer: int free; free = __LOG_BUF_LEN - log_next_idx; pr_info("early log buf free: %u(%u%%)\n", free, (free * 100) / __LOG_BUF_LEN); We support LOG_BUF_LEN of up to 1<<25 bytes. Since setup_log_buf() is called during early init, logbuf is mostly empty, so __LOG_BUF_LEN - log_next_idx is close to 1<<25. Thus when we multiply it by 100, we overflow signed integer value range: 100 is 2^6 + 2^5 + 2^2. Example, booting with LOG_BUF_LEN 1<<25 and log_buf_len=2G boot param: [ 0.075317] log_buf_len: -2147483648 bytes [ 0.075319] early log buf free: 33549896(-28%) Make "free" unsigned integer and use appropriate printk() specifier. Link: http://lkml.kernel.org/r/20181010113308.9337-1-sergey.senozhatsky@gmail.com To: Steven Rostedt Cc: linux-kernel@vger.kernel.org Cc: Sergey Senozhatsky Signed-off-by: Sergey Senozhatsky Signed-off-by: Petr Mladek Signed-off-by: Sasha Levin --- kernel/printk/printk.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c index 5b33c14ab8b25..4e50beb162c00 100644 --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -1099,7 +1099,7 @@ void __init setup_log_buf(int early) { unsigned long flags; char *new_log_buf; - int free; + unsigned int free; if (log_buf != __log_buf) return; -- 2.20.1