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Date:   Mon, 19 Aug 2019 04:14:11 +0800
From:   Gao Xiang <hsiangkao@aol.com>
To:     Christoph Hellwig <hch@infradead.org>,
        "Theodore Y. Ts'o" <tytso@mit.edu>,
        Eric Biggers <ebiggers@kernel.org>,
        Richard Weinberger <richard@nod.at>
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Jan Kara <jack@suse.cz>, Chao Yu <yuchao0@huawei.com>,
        Dave Chinner <david@fromorbit.com>,
        David Sterba <dsterba@suse.cz>, Miao Xie <miaoxie@huawei.com>,
        devel <devel@driverdev.osuosl.org>,
        Stephen Rothwell <sfr@canb.auug.org.au>,
        Darrick <darrick.wong@oracle.com>,
        Amir Goldstein <amir73il@gmail.com>,
        linux-erofs <linux-erofs@lists.ozlabs.org>,
        Al Viro <viro@zeniv.linux.org.uk>,
        Jaegeuk Kim <jaegeuk@kernel.org>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        Li Guifu <bluce.liguifu@huawei.com>,
        Fang Wei <fangwei1@huawei.com>, Pavel Machek <pavel@denx.de>,
        linux-fsdevel <linux-fsdevel@vger.kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        torvalds <torvalds@linux-foundation.org>
Subject: Re: [PATCH] erofs: move erofs out of staging
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Hi all,

On Mon, Aug 19, 2019 at 02:16:55AM +0800, Gao Xiang wrote:
> Hi Hch,
> 
> On Sun, Aug 18, 2019 at 10:47:02AM -0700, Christoph Hellwig wrote:
> > On Sun, Aug 18, 2019 at 10:29:38AM -0700, Eric Biggers wrote:
> > > Not sure what you're even disagreeing with, as I *do* expect new filesystems to
> > > be held to a high standard, and to be written with the assumption that the
> > > on-disk data may be corrupted or malicious.  We just can't expect the bar to be
> > > so high (e.g. no bugs) that it's never been attained by *any* filesystem even
> > > after years/decades of active development.  If the developers were careful, the
> > > code generally looks robust, and they are willing to address such bugs as they
> > > are found, realistically that's as good as we can expect to get...
> >
> > Well, the impression I got from Richards quick look and the reply to it is
> > that there is very little attempt to validate the ondisk data structure
> > and there is absolutely no priority to do so.  Which is very different
> > from there is a bug or two here and there.
> 
> As my second reply to Richard, I didn't fuzz all the on-disk fields for EROFS.
> and as my reply to Richard / Greg, current EROFS is used on the top of dm-verity.
> 
> I cannot say how well EROFS will be performed on malformed images (and you can
> also find the bug richard pointed out is a miswritten break->continue by myself).
> 
> I posted the upstream EROFS post on July 4, 2019 and a month and a half later,
> no one can tell me (yes, thanks for kind people reply me about their suggestion)
> what we should do next (you can see these emails, I sent many times) to meet
> the minimal upstream requirements and rare people can even dip into my code.
> 
> That is all I want to say. I will work on autofuzz these days, and I want to
> know how to meet your requirements on this (you can tell us your standard,
> how well should we do).
> 
> OK, you don't reply to my post once, I have no idea how to get your first reply.

I have made a simple fuzzer to inject messy in inode metadata,
dir data, compressed indexes and super block,
https://git.kernel.org/pub/scm/linux/kernel/git/xiang/erofs-utils.git/commit/?h=experimental-fuzzer

I am testing with some given dirs and the following script.
Does it look reasonable?

# !/bin/bash

mkdir -p mntdir

for ((i=0; i<1000; ++i)); do
	mkfs/mkfs.erofs -F$i testdir_fsl.fuzz.img testdir_fsl > /dev/null 2>&1
	umount mntdir
	mount -t erofs -o loop testdir_fsl.fuzz.img mntdir
	for j in `find mntdir -type f`; do
		md5sum $j > /dev/null
	done
done

Thanks,
Gao Xiang

> 
> Thanks,
> Gao Xiang
>