From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755892Ab2GaE5R (ORCPT ); Tue, 31 Jul 2012 00:57:17 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:48786 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755639Ab2GaEu4 (ORCPT ); Tue, 31 Jul 2012 00:50:56 -0400 Message-Id: <20120731044317.184294372@decadent.org.uk> User-Agent: quilt/0.60-1 Date: Tue, 31 Jul 2012 05:43:47 +0100 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Jan Kara Subject: [ 37/73] udf: Improve table length check to avoid possible overflow In-Reply-To: <20120731044310.013763753@decadent.org.uk> X-SA-Exim-Connect-IP: 2001:470:1f08:1539:21c:bfff:fe03:f805 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.2-stable review patch. If anyone has any objections, please let me know. ------------------ From: Jan Kara commit 57b9655d01ef057a523e810d29c37ac09b80eead upstream. When a partition table length is corrupted to be close to 1 << 32, the check for its length may overflow on 32-bit systems and we will think the length is valid. Later on the kernel can crash trying to read beyond end of buffer. Fix the check to avoid possible overflow. Reported-by: Ben Hutchings Signed-off-by: Jan Kara Signed-off-by: Ben Hutchings --- fs/udf/super.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/udf/super.c b/fs/udf/super.c index 8a75838..dcbf987 100644 --- a/fs/udf/super.c +++ b/fs/udf/super.c @@ -1340,7 +1340,7 @@ static int udf_load_logicalvol(struct super_block *sb, sector_t block, BUG_ON(ident != TAG_IDENT_LVD); lvd = (struct logicalVolDesc *)bh->b_data; table_len = le32_to_cpu(lvd->mapTableLength); - if (sizeof(*lvd) + table_len > sb->s_blocksize) { + if (table_len > sb->s_blocksize - sizeof(*lvd)) { udf_err(sb, "error loading logical volume descriptor: " "Partition table too long (%u > %lu)\n", table_len, sb->s_blocksize - sizeof(*lvd));