On 6.08.21 г. 14:33, Qu Wenruo wrote:
> There is a kernel regression for btrfs, that when passing non-existing
> devid to "btrfs device remove" command, kernel will crash due to NULL
> pointer dereference.
>
> The test case is for such regression, it will:
>
> - Create and mount an empty single-device btrfs
> - Try to remove devid 3, which doesn't exist for above fs
> - Make sure the command exits properly with expected error message
>
> The kernel fix is titled "btrfs: fix NULL pointer dereference when
> deleting device by invalid id".
>
> Signed-off-by: Qu Wenruo <wqu@xxxxxxxx>
> ---
> Changelog:
> v2:
> - Change the subject to also verify the error behavior
> - Include the error message into golden output
> - Also verify the return value of btrfs command
> ---
> tests/btrfs/244 | 47 +++++++++++++++++++++++++++++++++++++++++++++
> tests/btrfs/244.out | 2 ++
> 2 files changed, 49 insertions(+)
> create mode 100755 tests/btrfs/244
> create mode 100644 tests/btrfs/244.out
>
> diff --git a/tests/btrfs/244 b/tests/btrfs/244
> new file mode 100755
> index 00000000..fbefeedf
> --- /dev/null
> +++ b/tests/btrfs/244
> @@ -0,0 +1,47 @@
> +#! /bin/bash
> +# SPDX-License-Identifier: GPL-2.0
> +# Copyright (c) 2021 SUSE Linux Products GmbH. All Rights Reserved.
> +#
> +# FS QA Test 244
> +#
> +# Make sure "btrfs device remove" won't crash when non-existing devid
> +# is provided
> +#
> +. ./common/preamble
> +_begin_fstest auto quick volume dangerous
> +
> +# Override the default cleanup function.
> +# _cleanup()
> +# {
> +# cd /
> +# rm -r -f $tmp.*
> +# }
> +
> +# Import common functions.
> +# . ./common/filter
> +
> +# real QA test starts here
> +
> +# Modify as appropriate.
> +_supported_fs btrfs
> +_require_scratch
> +
> +_scratch_mkfs >> $seqres.full 2>&1
> +_scratch_mount
> +
> +# Above created fs only contains one device with devid 1, device remove 3
> +# should just fail with proper error message showing devid 3 can't be found.
> +# Although on unpatched kernel, this will trigger a NULL pointer dereference.
> +$BTRFS_UTIL_PROG device remove 3 $SCRATCH_MNT
> +ret=$?
> +
> +if [ $ret -ne 1 ]; then
> + echo "Unexpected return value from btrfs command, has $ret expected 1"
> +fi
<rant>
This just shows how broken progs are w.r.t return values. The generally
accepted return value is 0 on success, yet it returns 1 on success since
the functions implementing this functionality in progs treat the return
value as a boolean.
</rant>
> +
> +# Fstests will automatically check the filesystem to make sure metadata is not
> +# corrupted.
> +
> +# success, all done
> +status=0
> +exit
> diff --git a/tests/btrfs/244.out b/tests/btrfs/244.out
> new file mode 100644
> index 00000000..629adf2a
> --- /dev/null
> +++ b/tests/btrfs/244.out
> @@ -0,0 +1,2 @@
> +QA output created by 244
> +ERROR: error removing devid 3: No such file or directory
>
