linux/fs/nilfs2
Ryusuke Konishi 42560f9c92 nilfs2: fix sysfs interface lifetime
The current nilfs2 sysfs support has issues with the timing of creation
and deletion of sysfs entries, potentially leading to null pointer
dereferences, use-after-free, and lockdep warnings.

Some of the sysfs attributes for nilfs2 per-filesystem instance refer to
metadata file "cpfile", "sufile", or "dat", but
nilfs_sysfs_create_device_group that creates those attributes is executed
before the inodes for these metadata files are loaded, and
nilfs_sysfs_delete_device_group which deletes these sysfs entries is
called after releasing their metadata file inodes.

Therefore, access to some of these sysfs attributes may occur outside of
the lifetime of these metadata files, resulting in inode NULL pointer
dereferences or use-after-free.

In addition, the call to nilfs_sysfs_create_device_group() is made during
the locking period of the semaphore "ns_sem" of nilfs object, so the
shrinker call caused by the memory allocation for the sysfs entries, may
derive lock dependencies "ns_sem" -> (shrinker) -> "locks acquired in
nilfs_evict_inode()".

Since nilfs2 may acquire "ns_sem" deep in the call stack holding other
locks via its error handler __nilfs_error(), this causes lockdep to report
circular locking.  This is a false positive and no circular locking
actually occurs as no inodes exist yet when
nilfs_sysfs_create_device_group() is called.  Fortunately, the lockdep
warnings can be resolved by simply moving the call to
nilfs_sysfs_create_device_group() out of "ns_sem".

This fixes these sysfs issues by revising where the device's sysfs
interface is created/deleted and keeping its lifetime within the lifetime
of the metadata files above.

Link: https://lkml.kernel.org/r/20230330205515.6167-1-konishi.ryusuke@gmail.com
Fixes: dd70edbde2 ("nilfs2: integrate sysfs support into driver")
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Reported-by: syzbot+979fa7f9c0d086fdc282@syzkaller.appspotmail.com
  Link: https://lkml.kernel.org/r/0000000000003414b505f7885f7e@google.com
Reported-by: syzbot+5b7d542076d9bddc3c6a@syzkaller.appspotmail.com
  Link: https://lkml.kernel.org/r/0000000000006ac86605f5f44eb9@google.com
Cc: Viacheslav Dubeyko <slava@dubeyko.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-04-05 18:06:24 -07:00
..
alloc.c nilfs2: remove filenames from file comments 2021-11-09 10:02:52 -08:00
alloc.h nilfs2: remove filenames from file comments 2021-11-09 10:02:52 -08:00
bmap.c nilfs2: remove filenames from file comments 2021-11-09 10:02:52 -08:00
bmap.h nilfs2: remove filenames from file comments 2021-11-09 10:02:52 -08:00
btnode.c nilfs2: replace obvious uses of b_page with b_folio 2023-01-18 17:12:41 -08:00
btnode.h fs/nilfs2: Use the enum req_op and blk_opf_t types 2022-07-14 12:14:33 -06:00
btree.c nilfs2: initialize "struct nilfs_binfo_dat"->bi_pad field 2023-04-05 18:06:23 -07:00
btree.h nilfs2: remove filenames from file comments 2021-11-09 10:02:52 -08:00
cpfile.c nilfs2: remove filenames from file comments 2021-11-09 10:02:52 -08:00
cpfile.h nilfs2: remove filenames from file comments 2021-11-09 10:02:52 -08:00
dat.c nilfs2: prevent WARNING in nilfs_dat_commit_end() 2023-02-02 22:50:10 -08:00
dat.h nilfs2: remove filenames from file comments 2021-11-09 10:02:52 -08:00
dir.c nilfs2: Remove check for PageError 2022-06-29 08:51:07 -04:00
direct.c nilfs2: initialize "struct nilfs_binfo_dat"->bi_pad field 2023-04-05 18:06:23 -07:00
direct.h nilfs2: remove filenames from file comments 2021-11-09 10:02:52 -08:00
export.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
file.c nilfs2: remove filenames from file comments 2021-11-09 10:02:52 -08:00
gcinode.c nilfs2: replace obvious uses of b_page with b_folio 2023-01-18 17:12:41 -08:00
ifile.c nilfs2: remove filenames from file comments 2021-11-09 10:02:52 -08:00
ifile.h nilfs2: remove filenames from file comments 2021-11-09 10:02:52 -08:00
inode.c fs: port inode_init_owner() to mnt_idmap 2023-01-19 09:24:28 +01:00
ioctl.c nilfs2: fix kernel-infoleak in nilfs_ioctl_wrap_copy() 2023-03-23 17:18:32 -07:00
Kconfig fs: build the legacy direct I/O code conditionally 2023-01-26 10:30:56 -07:00
Makefile License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
mdt.c nilfs2: replace obvious uses of b_page with b_folio 2023-01-18 17:12:41 -08:00
mdt.h nilfs2: fix lockdep warnings during disk space reclamation 2022-04-01 11:46:09 -07:00
namei.c fs: port ->rename() to pass mnt_idmap 2023-01-19 09:24:26 +01:00
nilfs.h fs: port ->permission() to pass mnt_idmap 2023-01-19 09:24:28 +01:00
page.c nilfs2: convert nilfs_clear_dirty_pages() to use filemap_get_folios_tag() 2023-02-02 22:33:18 -08:00
page.h nilfs2: get rid of nilfs_mapping_init() 2022-04-01 11:46:09 -07:00
recovery.c fs: Remove aop flags parameter from block_write_begin() 2022-05-08 14:28:19 -04:00
segbuf.c Merge branch 'akpm' (patches from Andrew) 2022-03-22 16:11:53 -07:00
segbuf.h nilfs2: remove filenames from file comments 2021-11-09 10:02:52 -08:00
segment.c nilfs2: fix potential UAF of struct nilfs_sc_info in nilfs_segctor_thread() 2023-04-05 18:06:23 -07:00
segment.h nilfs2: remove filenames from file comments 2021-11-09 10:02:52 -08:00
sufile.c nilfs2: fix nilfs_sufile_mark_dirty() not set segment usage as dirty 2022-11-22 18:50:45 -08:00
sufile.h nilfs2: remove filenames from file comments 2021-11-09 10:02:52 -08:00
super.c nilfs2: fix sysfs interface lifetime 2023-04-05 18:06:24 -07:00
sysfs.c nilfs2: use default_groups in kobj_type 2021-12-29 10:53:48 +01:00
sysfs.h nilfs2: remove filenames from file comments 2021-11-09 10:02:52 -08:00
the_nilfs.c nilfs2: fix sysfs interface lifetime 2023-04-05 18:06:24 -07:00
the_nilfs.h nilfs2: remove filenames from file comments 2021-11-09 10:02:52 -08:00