From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759850Ab0COIV3 (ORCPT ); Mon, 15 Mar 2010 04:21:29 -0400 Received: from mail-fx0-f227.google.com ([209.85.220.227]:38981 "EHLO mail-fx0-f227.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759829Ab0COIV2 (ORCPT ); Mon, 15 Mar 2010 04:21:28 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=date:from:to:cc:subject:message-id:mail-followup-to:mime-version :content-type:content-disposition:user-agent; b=fOghTW5X92846Ami4OjTbkZT6xxuZojsLa6FPdSiZQgU0YO2+HhPQJDLJM2/okUm48 suZufmLGu93GY9RnWFwEDDpl0ttVDufpDtPqRGiQ5mMtyKN5E3Vo4ocSREcRr64Gup0n YSVAFK4Nq2M3CTX2NS8aZlkb9FgYFLC+e4gC8= Date: Mon, 15 Mar 2010 11:21:13 +0300 From: Dan Carpenter To: Jan Kara Cc: Pekka Enberg , Hannes Eder , Akinobu Mita , Al Viro , linux-kernel@vger.kernel.org, kernel-janitors@vger.kernel.org Subject: [patch] udf: potential integer overflow Message-ID: <20100315082113.GC18181@bicker> Mail-Followup-To: Dan Carpenter , Jan Kara , Pekka Enberg , Hannes Eder , Akinobu Mita , Al Viro , linux-kernel@vger.kernel.org, kernel-janitors@vger.kernel.org MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org bloc->logicalBlockNum is unsigned so it's never less than zero. When I saw that, it made me worry that "bloc->logicalBlockNum + count" could overflow. That's why I changed the check for less than zero to an overflow check. (The test works because "count" is also unsigned.) Signed-off-by: Dan Carpenter --- GCC 4.1 apparently optimizes overflow checks like this away, but it should work for other versions of gcc. I tested with GCC 4.3. http://www.fefe.de/intof.html diff --git a/fs/udf/balloc.c b/fs/udf/balloc.c index 19626e2..9a9378b 100644 --- a/fs/udf/balloc.c +++ b/fs/udf/balloc.c @@ -125,9 +125,8 @@ static void udf_bitmap_free_blocks(struct super_block *sb, mutex_lock(&sbi->s_alloc_mutex); partmap = &sbi->s_partmaps[bloc->partitionReferenceNum]; - if (bloc->logicalBlockNum < 0 || - (bloc->logicalBlockNum + count) > - partmap->s_partition_len) { + if (bloc->logicalBlockNum + count < count || + (bloc->logicalBlockNum + count) > partmap->s_partition_len) { udf_debug("%d < %d || %d + %d > %d\n", bloc->logicalBlockNum, 0, bloc->logicalBlockNum, count, partmap->s_partition_len); @@ -393,9 +392,8 @@ static void udf_table_free_blocks(struct super_block *sb, mutex_lock(&sbi->s_alloc_mutex); partmap = &sbi->s_partmaps[bloc->partitionReferenceNum]; - if (bloc->logicalBlockNum < 0 || - (bloc->logicalBlockNum + count) > - partmap->s_partition_len) { + if (bloc->logicalBlockNum + count < count || + (bloc->logicalBlockNum + count) > partmap->s_partition_len) { udf_debug("%d < %d || %d + %d > %d\n", bloc->logicalBlockNum, 0, bloc->logicalBlockNum, count, partmap->s_partition_len);