On Fri, Aug 6, 2021 at 11:47 AM Qu Wenruo <wqu@xxxxxxxx> 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
>
> The fix is titled "btrfs: fix NULL pointer dereference when deleting
> device by invalid id".
>
> Signed-off-by: Qu Wenruo <wqu@xxxxxxxx>
> ---
> tests/btrfs/244 | 42 ++++++++++++++++++++++++++++++++++++++++++
> tests/btrfs/244.out | 2 ++
> 2 files changed, 44 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..56eb9e8c
> --- /dev/null
> +++ b/tests/btrfs/244
> @@ -0,0 +1,42 @@
> +#! /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 >> $seqres.full 2>&1
> +_scratch_mount
> +
> +# Above created fs only contains one device with devid 1, device remove 3
> +# should just fail.
> +# We don't care about the failure itself, but care whether this would cause
> +# kernel crash.
> +$BTRFS_UTIL_PROG device remove 3 $SCRATCH_MNT >> $seqres.full 2>&1
While here we could also check that the operation fails. That avoids
adding yet another test case if one day we have a regression where the
operation returns success instead of an error.
In fact the test subject and goal should be to verify that removing a
non-existing device fails and does not cause any harm (kernel crash,
metadata corruption, etc).
Thanks.
> +
> +echo "Silence is golden"
> +
> +# success, all done
> +status=0
> +exit
> diff --git a/tests/btrfs/244.out b/tests/btrfs/244.out
> new file mode 100644
> index 00000000..440da1f2
> --- /dev/null
> +++ b/tests/btrfs/244.out
> @@ -0,0 +1,2 @@
> +QA output created by 244
> +Silence is golden
> --
> 2.31.1
>
--
Filipe David Manana,
“Whether you think you can, or you think you can't — you're right.”
