From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935039AbbKTVbn (ORCPT ); Fri, 20 Nov 2015 16:31:43 -0500 Received: from mx1.redhat.com ([209.132.183.28]:43228 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934555AbbKTVbm (ORCPT ); Fri, 20 Nov 2015 16:31:42 -0500 From: Jeff Moyer To: Kees Cook Cc: Andrew Morton , Jens Axboe , Dan Carpenter , linux-block@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH][RESEND] mac: validate mac_partition is within sector References: <20151120011854.GA12836@www.outflux.net> X-PGP-KeyID: 1F78E1B4 X-PGP-CertKey: F6FE 280D 8293 F72C 65FD 5A58 1FF8 A7CA 1F78 E1B4 X-PCLoadLetter: What the f**k does that mean? Date: Fri, 20 Nov 2015 16:31:39 -0500 In-Reply-To: <20151120011854.GA12836@www.outflux.net> (Kees Cook's message of "Thu, 19 Nov 2015 17:18:54 -0800") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.3 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Kees Cook writes: > If md->signature == MAC_DRIVER_MAGIC and md->block_size == 1023, a single > 512 byte sector would be read (secsize / 512). However the partition > structure would be located past the end of the buffer (secsize % 512). Do we even want to support non-power-of-two block sizes? -Jeff > > Signed-off-by: Kees Cook > Cc: stable@vger.kernel.org > --- > There doesn't seem to be a mac partition maintainer... > --- > block/partitions/mac.c | 10 +++++++--- > 1 file changed, 7 insertions(+), 3 deletions(-) > > diff --git a/block/partitions/mac.c b/block/partitions/mac.c > index c2c48ec64b27..621317ac4d59 100644 > --- a/block/partitions/mac.c > +++ b/block/partitions/mac.c > @@ -32,7 +32,7 @@ int mac_partition(struct parsed_partitions *state) > Sector sect; > unsigned char *data; > int slot, blocks_in_map; > - unsigned secsize; > + unsigned secsize, datasize, partoffset; > #ifdef CONFIG_PPC_PMAC > int found_root = 0; > int found_root_goodness = 0; > @@ -50,10 +50,14 @@ int mac_partition(struct parsed_partitions *state) > } > secsize = be16_to_cpu(md->block_size); > put_dev_sector(sect); > - data = read_part_sector(state, secsize/512, §); > + datasize = round_down(secsize, 512); > + data = read_part_sector(state, datasize / 512, §); > if (!data) > return -1; > - part = (struct mac_partition *) (data + secsize%512); > + partoffset = secsize % 512; > + if (partoffset + sizeof(*part) > datasize) > + return -1; > + part = (struct mac_partition *) (data + partoffset); > if (be16_to_cpu(part->signature) != MAC_PARTITION_MAGIC) { > put_dev_sector(sect); > return 0; /* not a MacOS disk */ > -- > 1.9.1