linux-ext4 - Re: [Bugme-new] [Bug 11266] New: unable to handle kernel paging request in ext2_free

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Message-ID: <20080819105111.GK8997@lh.kyla.fi>
Date:	Tue, 19 Aug 2008 13:51:12 +0300
From:	Sami Liedes <sliedes@...hut.fi>
To:	Jan Kara <jack@...e.cz>
Cc:	Andreas Dilger <adilger@....com>,
	"Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	bugme-daemon@...zilla.kernel.org, linux-ext4@...r.kernel.org
Subject: Re: [Bugme-new] [Bug 11266] New: unable to handle kernel paging
	request in ext2_free_blocks

On Tue, Aug 19, 2008 at 11:13:39AM +0200, Jan Kara wrote:
> > Isn't equivalent checking done in ext2_check_descriptors()?  It would make
> > sense to abstract out the "check one group and return error" code and use
> > it in both places.
>   Actually yes, it is. Good point. Sami, is it the case that you have
> mounted the filesystem, then intentionally corrupted it and after that
> the kernel oopsed (as opposed to first corrupting the filesystem image and
> mounting it after that)? That would explain how corrupted values could get
> to read_block_bitmap() even though ext2_check_descriptors() checked them.

No, that's not what I do. I corrupt the fs before mounting it, then
mount it, perform normal filesystem operations on it and unmount it.

Here's the most current script I use (zzuf is the fuzzer):

------------------------------------------------------------
#!/bin/sh

if [ "`hostname`" != "fstest" ]; then
   echo "This is a dangerous script."
   echo "Set your hostname to \`fstest\' if you want to use it."
   exit 1
fi

umount /dev/hdb
umount /dev/hdc
/etc/init.d/sysklogd stop
/etc/init.d/klogd stop
/etc/init.d/cron stop
mount /dev/hda / -t ext3 -o remount,ro || exit 1

#ulimit -t 20

for ((s=$1; s<1000000000; s++)); do
  umount /mnt
  echo '***** zzuffing *****' seed $s
  zzuf -r 0:0.03 -s $s </dev/hdc >/dev/hdb || exit
  mount /dev/hdb /mnt -t ext2 -o errors=continue || continue
  cd /mnt || continue
  timeout 30 cp -r doc doc2 >&/dev/null
  timeout 30 find -xdev >&/dev/null
  timeout 30 find -xdev -print0 2>/dev/null |xargs -0 touch -- 2>/dev/null
  timeout 30 mkdir tmp >&/dev/null
  timeout 30 echo whoah >tmp/filu 2>/dev/null
  timeout 30 rm -rf /mnt/* >&/dev/null
  cd /
done
------------------------------------------------------------

	Sami
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