* Re: [PATCH] xfs: testcase for kernelspace xfs_fsr extent handling flaw
2016-11-05 9:40 ` [PATCH] xfs: testcase for kernelspace xfs_fsr extent handling flaw Eryu Guan
@ 2016-11-05 19:38 ` Eric Sandeen
0 siblings, 0 replies; 2+ messages in thread
From: Eric Sandeen @ 2016-11-05 19:38 UTC (permalink / raw)
To: Eryu Guan; +Cc: Eric Sandeen, fstests, linux-xfs
> OnNov 5, 2016, at 4:40 AM, Eryu Guan <eguan@redhat.com> wrote:
>
> [fixed linux-xfs list address on reply]
>
>> On Fri, Nov 04, 2016 at 09:00:09PM -0500, Eric Sandeen wrote:
>> This is a testcase for a bug which goes way back; googling
>> "xfs_trans_log_inode NULL pointer dereference" yields sporadic
>> reports over several years.
>>
>> The test sets up several two-extent files with speculative
>> preallocation on them, and then runs xfs_fsr. The kernelside
>> code ignores the preallocation, and therefore sets up the
>> temporary inode incorrectly after the inode fork swap.
>>
>> It is a "dangerous" test because the extent mishandling on
>> the temporary inode causes a null pointer dereference and
>> oops when the inode's i_itemp pointer gets overwritten
>> and we blow up in logging code that tries to use it.
>>
>> Signed-off-by: Eric Sandeen <sandeen@redhat.com>
>
> Tested with 4.9-rc3 kernel and saw NULL pointer dereference as expected.
> And test passed without problem after applying "xfs: fix up
> xfs_swap_extent_forks inline extent handling".
>
> Just some tiny issues inline:
Sorry about those and thanks for fixing them up!
>
>> ---
>>
>> diff --git a/tests/xfs/118 b/tests/xfs/118
>> new file mode 100755
>> index 0000000..d2c9080
>> --- /dev/null
>> +++ b/tests/xfs/118
>> @@ -0,0 +1,99 @@
>> +#! /bin/bash
>> +# FS QA Test 118
>> +#
>> +# Test xfs_fsr's handling of 2-extent files with preallocation
>> +#
>> +# An error in xfs_swap_extent_forks() incorrectly set up the
>> +# temporary inode's if_extents pointer to inline, leading to
>> +# in-memory corruption when the temporary inode was released
>
> Trailing whitespace here
>
>> +# and torn down; i_itemp and d_ops got overwritten with zeros,
>> +# which led to an oops in xfs_trans_log_inode down the fput path.
>> +#
>> +# Fixed upstream by proper nextents counting using
>
> And here :)
>
>> +# ip->i_df.if_bytes not ip->i_d.di_nextents in xfs_swap_extent_forks
>> +#
>> +#-----------------------------------------------------------------------
>> +# Copyright (c) 2016 Red Hat, inc. All Rights Reserved.
>> +#
>> +# This program is free software; you can redistribute it and/or
>> +# modify it under the terms of the GNU General Public License as
>> +# published by the Free Software Foundation.
>> +#
>> +# This program is distributed in the hope that it would be useful,
>> +# but WITHOUT ANY WARRANTY; without even the implied warranty of
>> +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
>> +# GNU General Public License for more details.
>> +#
>> +# You should have received a copy of the GNU General Public License
>> +# along with this program; if not, write the Free Software Foundation,
>> +# Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
>> +#-----------------------------------------------------------------------
>> +#
>> +
>> +seq=`basename $0`
>> +seqres=$RESULT_DIR/$seq
>> +echo "QA output created by $seq"
>> +
>> +here=`pwd`
>> +tmp=/tmp/$$
>> +status=1 # failure is the default!
>> +trap "_cleanup; exit \$status" 0 1 2 3 15
>> +
>> +_cleanup()
>> +{
>> + cd /
>> + rm -f $tmp.*
>> +}
>> +
>> +# get standard environment, filters and checks
>> +. ./common/rc
>> +. ./common/filter
>> +
>> +# remove previous $seqres.full before test
>> +rm -f $seqres.full
>> +
>> +_supported_fs xfs
>> +_supported_os IRIX Linux
>> +
>> +_require_scratch
>> +_require_command "$XFS_FSR_PROG" "xfs_fsr"
>> +
>> +# 50M
>> +_scratch_mkfs_sized $((50 * 1024 * 1024)) >> $seqres.full 2>&1
>> +_scratch_mount
>> +
>> +echo "Silence is golden"
>> +
>> +# Fragment freespace
>> +# The aim is to create a fragmented two-extent file *with* prealloc
>> +# so make the free holes big enough that a 2-extent file will have
>> +# preallocation added. Let's say... 64k free chunks.
>> +
>> +$XFS_IO_PROG -fs -c "falloc 0 40000k" $SCRATCH_MNT/fill >> $seqres.full 2>&1
>> +sync
>> +
>> +dd if=/dev/zero of=$SCRATCH_MNT/remainder oflag=direct > /dev/null 2>&1
>> +
>> +# Free up a bunch of 64k chunks
>> +for i in `seq 0 68 40000`; do
>> + $XFS_IO_PROG -fs -c "unresvsp ${i}k 64k" $SCRATCH_MNT/fill
>> +done
>> +
>> +# Create 2-extent files w/ preallocation (via extending writes)
>> +for I in `seq 1 64`; do
>> + $XFS_IO_PROG -f -c "pwrite 0 64k" $SCRATCH_MNT/newfile-$I \
>> + >> $seqres.full 2>&1
>> + $XFS_IO_PROG -f -c "pwrite 64k 64k" $SCRATCH_MNT/newfile-$I \
>> + >> $seqres.full 2>&1
>> +done
>> +# sync to get extents on disk so fsr sees them
>> +sync
>> +
>> +# Free up some space for defragmentation temp file
>> +rm -f $SCRATCH_MNT/fill
>> +
>> +$XFS_FSR_PROG -vd $SCRATCH_MNT/newfile* >> $seqres.full 2>&1
>> +
>> +# success, all done
>> +status=0
>> +exit
>> diff --git a/tests/xfs/118.out b/tests/xfs/118.out
>> new file mode 100644
>> index 0000000..3daed86
>> --- /dev/null
>> +++ b/tests/xfs/118.out
>> @@ -0,0 +1,2 @@
>> +QA output created by 118
>> +Silence is golden
>> diff --git a/tests/xfs/group b/tests/xfs/group
>> index 3296eb9..0a7a0a8 100644
>> --- a/tests/xfs/group
>> +++ b/tests/xfs/group
>> @@ -115,6 +115,7 @@
>> 115 parent attr
>> 116 quota auto quick
>> 117 fuzzers
>> +118 growfs dangerous
> ^^^^^^ should be "fsr" I think.
>
> As this test crashes current upstream kernel, I'm going to let the
> kenrel fixes go upstream first, then merge this patch, so it won't break
> normal upstream kernel tests by crashing the test hosts.
>
> Then 118 could be in 'auto' and 'quick' group. I can fix all the minor
> issues at commit time.
>
> Thanks,
> Eryu
>
>> 119 log v2log auto freeze dangerous
>> 120 fuzzers
>> 121 log auto quick
>>
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