dc3216b141
For keyed filesystems that recycle superblocks based on s_fs_info or
information contained therein s_fs_info must be kept as long as the
superblock is on the filesystem type super list. This isn't guaranteed
as s_fs_info will be freed latest in sb->kill_sb().
The fix is simply to perform notification and list removal in
kill_anon_super(). Any filesystem needs to free s_fs_info after they
call the kill_*() helpers. If they don't they risk use-after-free right
now so fixing it here is guaranteed that s_fs_info remain valid.
For block backed filesystems notifying in pass sb->kill_sb() in
deactivate_locked_super() remains unproblematic and is required because
multiple other block devices can be shut down after kill_block_super()
has been called from a filesystem's sb->kill_sb() handler. For example,
ext4 and xfs close additional devices. Block based filesystems don't
depend on s_fs_info (btrfs does use s_fs_info but also uses
kill_anon_super() and not kill_block_super().).
Sorry for that braino. Goal should be to unify this behavior during this
cycle obviously. But let's please do a simple bugfix now.
Fixes: 2c18a63b760a ("super: wait until we passed kill super")
Fixes: syzbot+5b64180f8d9e39d3f061@syzkaller.appspotmail.com
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reported-by: syzbot+5b64180f8d9e39d3f061@syzkaller.appspotmail.com
Message-Id: <20230828-vfs-super-fixes-v1-2-b37a4a04a88f@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.