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=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,USER_AGENT_GIT 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 A1CEEC43441 for ; Wed, 10 Oct 2018 10:38:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 575D7214DA for ; Wed, 10 Oct 2018 10:38:20 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="J1zMt6FW" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 575D7214DA 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 S1726670AbeJJR7v (ORCPT ); Wed, 10 Oct 2018 13:59:51 -0400 Received: from mail-pg1-f196.google.com ([209.85.215.196]:40331 "EHLO mail-pg1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726479AbeJJR7u (ORCPT ); Wed, 10 Oct 2018 13:59:50 -0400 Received: by mail-pg1-f196.google.com with SMTP id n31-v6so2325000pgm.7 for ; Wed, 10 Oct 2018 03:38:18 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=tvmYdmLOghzWeLLbc6LJKHz7tDETJvtRKEgTias8DaY=; b=J1zMt6FWWhNnGoyI6qHBdfzWzIO5az7CpNXqVRoStzYkT8jrkkC5CzQcMpe76MruMB dGMzvGh/ZhoSr08gMPXNJKLcZGNr/tGLqYh5oPTFKIt7py+A3IzQLFJCFjiVzLkaHSi3 xBXHY3n/wrychlqHXe/sDDBsQxD4hNfsqSg3UO54iWW1s53GZzUXJ6hs80lQW9qUpAQM ABfSEY+0v/VNECj/XyX4Jr5OrEtSSP153GLQWHPG5ZL9+101CbL00jjOi5rlsrh9OVPL HgyICyAaDDPyqlWYnAz8OQ8A+gKz7z3vwhg4iEefa1LRlHDw8fZX/ZXl8ycNEwzFFQH4 dzeg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=tvmYdmLOghzWeLLbc6LJKHz7tDETJvtRKEgTias8DaY=; b=Oizk29yOEwWP4Wr0f/yHX2KracdpFcjrP3m06af3W2wSPhTpyY9UY6CJARMhnRQgS9 A/CjsiyeIci0JLVtZKx0Iozh9hnMoE0oy6hnlTgcZOm1CZbomnB6KSWHfvsN7s9S/lNT c6B3ifLtw5ytDntrhbSRpX7ruOQ+DnhC2e8d2nPffCQ7DhtGg4FEQm0D3uu3PdHMmgAd GBTONQZpkSjOO8RmFsJSqX+JjMDx+3PSyH4ErmNOdXEvXC1G28eLVY5R3S2El/70Wx06 4mwCN0gkiEX4lK6VDq95F+/eMCCKqQHdKgaGavSRAgspCN9oxyUZ8mfVZt3mXw2lpvQn QeqQ== X-Gm-Message-State: ABuFfoiKCT933LlsoLPuDqFZxoBHChyWcXenudFcL7iWonRufy13PuKU z/NL6+SenWDxrtsPlAzNjOw= X-Google-Smtp-Source: ACcGV60Dy5NXonwbPROiq/zUnuR9v3huWWbG6T6B8C/vBetFtcbqSdbSEiLiieyvYuoGXmaEap8k3w== X-Received: by 2002:a63:5d03:: with SMTP id r3-v6mr29632624pgb.445.1539167897368; Wed, 10 Oct 2018 03:38:17 -0700 (PDT) Received: from localhost.localdomain ([175.223.17.147]) by smtp.gmail.com with ESMTPSA id t4-v6sm27357448pfh.45.2018.10.10.03.38.13 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 10 Oct 2018 03:38:16 -0700 (PDT) From: Sergey Senozhatsky X-Google-Original-From: Sergey Senozhatsky To: Steven Rostedt , Petr Mladek Cc: linux-kernel@vger.kernel.org, Sergey Senozhatsky Subject: [PATCH] printk: fix integer overflow in setup_log_buf() Date: Wed, 10 Oct 2018 19:38:08 +0900 Message-Id: <20181010103808.882-1-sergey.senozhatsky@gmail.com> X-Mailer: git-send-email 2.19.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The way we calculate free 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 2G, since setup_log_buf() is called during early init logbuf is mostly empty, so __LOG_BUF_LEN - log_next_idx is close to 2G. When we multiply it by 100, we overflow signed integer value range. Example, booting with 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. Signed-off-by: Sergey Senozhatsky --- kernel/printk/printk.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c index c3f0e3927e77..c9e1d3bf695e 100644 --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -1083,7 +1083,7 @@ 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; @@ -1116,8 +1116,8 @@ void __init setup_log_buf(int early) memcpy(log_buf, __log_buf, __LOG_BUF_LEN); logbuf_unlock_irqrestore(flags); - pr_info("log_buf_len: %d bytes\n", log_buf_len); - pr_info("early log buf free: %d(%d%%)\n", + pr_info("log_buf_len: %u bytes\n", log_buf_len); + pr_info("early log buf free: %u(%u%%)\n", free, (free * 100) / __LOG_BUF_LEN); } -- 2.19.1