From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from aserp1040.oracle.com ([141.146.126.69]:41332 "EHLO aserp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752272AbcD2RJs (ORCPT ); Fri, 29 Apr 2016 13:09:48 -0400 Date: Fri, 29 Apr 2016 10:09:12 -0700 From: Liu Bo To: Qu Wenruo Cc: dsterba@suse.cz, linux-btrfs@vger.kernel.org, dsterba@suse.com Subject: Re: [PATCH] Btrfs: fix divide error upon chunk's stripe_len Message-ID: <20160429170912.GA17103@localhost.localdomain> Reply-To: bo.li.liu@oracle.com References: <1461718411-809-1-git-send-email-bo.li.liu@oracle.com> <20160427163903.GK29353@twin.jikos.cz> <20160427172335.GA15822@localhost.localdomain> <20160427173318.GN29353@twin.jikos.cz> <20160428174836.GA12012@localhost.localdomain> <6c444bbf-9a59-9c95-e691-a5ec52d5f688@cn.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <6c444bbf-9a59-9c95-e691-a5ec52d5f688@cn.fujitsu.com> Sender: linux-btrfs-owner@vger.kernel.org List-ID: On Fri, Apr 29, 2016 at 11:20:31AM +0800, Qu Wenruo wrote: > > > Liu Bo wrote on 2016/04/28 10:48 -0700: > >On Wed, Apr 27, 2016 at 07:33:18PM +0200, David Sterba wrote: > >>On Wed, Apr 27, 2016 at 10:23:35AM -0700, Liu Bo wrote: > >>>On Wed, Apr 27, 2016 at 06:39:03PM +0200, David Sterba wrote: > >>>>On Tue, Apr 26, 2016 at 05:53:31PM -0700, Liu Bo wrote: > >>>>>The struct 'map_lookup' uses type int for @stripe_len, while > >>>>>btrfs_chunk_stripe_len() can return a u64 value, and it may end up with > >>>>>@stripe_len being undefined value and it can lead to 'divide error' in > >>>>> __btrfs_map_block(). > >>>>> > >>>>>This changes 'map_lookup' to use type u64 for stripe_len, also right now > >>>>>we only use BTRFS_STRIPE_LEN for stripe_len, so this adds a valid checker for > >>>>>BTRFS_STRIPE_LEN. > >>>>> > >>>>>Reported-by: Vegard Nossum > >>>>>Reported-by: Quentin Casasnovas > >>>> > >>>>I smell some fuzzing :) do you have the image available? I'll add it to > >>>>the rest in btrfsprogs. > >>> > >>>Sure, it's on the way, I'll send it along with a patch for btrfsck (we > >>>have to add the same validation check for superblock and chunk in > >>>btrfsck.) > >> > >>Great! > >> > >>>>>Signed-off-by: Liu Bo > >>>>>--- > >>>>> fs/btrfs/volumes.c | 2 +- > >>>>> fs/btrfs/volumes.h | 2 +- > >>>>> 2 files changed, 2 insertions(+), 2 deletions(-) > >>>>> > >>>>>diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c > >>>>>index e2b54d5..b5cb859 100644 > >>>>>--- a/fs/btrfs/volumes.c > >>>>>+++ b/fs/btrfs/volumes.c > >>>>>@@ -6242,7 +6242,7 @@ static int read_one_chunk(struct btrfs_root *root, struct btrfs_key *key, > >>>>> "invalid chunk length %llu", length); > >>>>> return -EIO; > >>>>> } > >>>>>- if (!is_power_of_2(stripe_len)) { > >>>>>+ if (!is_power_of_2(stripe_len) || stripe_len != BTRFS_STRIPE_LEN) { > > > >We don't need the first 'is_power_of_2' check. > > > >And I think we may need to have another helper, such as btrfs_check_chunk_valid(), > >to cover all these (both current and future) validation checks. What do you think? > > > >Thanks, > > > >-liubo > > > > +1 for a btrfs_check_chunk_valid(). > > And I'm OK to remove is_power_of_2 check, as it's only used for future > stripe_len. > But we only support fix STRIPE_LEN, it's OK to remove it. OK. > > BTW, did it crash btrfs-progs? Yes, not really crash progs, but btrfsck doesn't detect errors. I've made a patch and I'm testing it to make sure everything works. Thanks, -liubo > > Thanks, > Qu > > >>>> > >>>>Unfortunatelly this will break current state, as mkfs does not set the > >>>>stripe length to 64k but to 4k. But the value is otherwise ignored in > >>>>kernel. > >>> > >>>This is chunk's stripe_len, not superblock's stripe_len: > >>> > >>>make_btrfs() { > >>> ... > >>> btrfs_set_super_stripesize(&super, cfg->stripesize); --> 4096 > >>> ... > >>> btrfs_set_chunk_stripe_len(buf, chunk, 64 * 1024); > >>>} > >> > >>Oh right, and the hardcoded stripe chunk size would need to be fixed in > >>a lot more places so it's fine. Consider this > >> > >>Reviewed-by: David Sterba > >> > >>and on the way to for-next. > >-- > >To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in > >the body of a message to majordomo@vger.kernel.org > >More majordomo info at http://vger.kernel.org/majordomo-info.html > > > > > >