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Zhen Lei 7e98111cb2 nilfs2: use refcount_dec_and_lock() to fix potential UAF 
commit 98e2e409e76ef7781d8511f997359e9c504a95c1 upstream.

When the refcount is decreased to 0, the resource reclamation branch is
entered.  Before CPU0 reaches the race point (1), CPU1 may obtain the
spinlock and traverse the rbtree to find 'root', see
nilfs_lookup_root().

Although CPU1 will call refcount_inc() to increase the refcount, it is
obviously too late.  CPU0 will release 'root' directly, CPU1 then
accesses 'root' and triggers UAF.

Use refcount_dec_and_lock() to ensure that both the operations of
decrease refcount to 0 and link deletion are lock protected eliminates
this risk.

	     CPU0                      CPU1
	nilfs_put_root():
		    <-------- (1)
				spin_lock(&nilfs->ns_cptree_lock);
				rb_erase(&root->rb_node, &nilfs->ns_cptree);
				spin_unlock(&nilfs->ns_cptree_lock);

	kfree(root);
		    <-------- use-after-free

  refcount_t: underflow; use-after-free.
  WARNING: CPU: 2 PID: 9476 at lib/refcount.c:28 \
  refcount_warn_saturate+0x1cf/0x210 lib/refcount.c:28
  Modules linked in:
  CPU: 2 PID: 9476 Comm: syz-executor.0 Not tainted 5.10.45-rc1+ #3
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), ...
  RIP: 0010:refcount_warn_saturate+0x1cf/0x210 lib/refcount.c:28
  ... ...
  Call Trace:
     __refcount_sub_and_test include/linux/refcount.h:283 [inline]
     __refcount_dec_and_test include/linux/refcount.h:315 [inline]
     refcount_dec_and_test include/linux/refcount.h:333 [inline]
     nilfs_put_root+0xc1/0xd0 fs/nilfs2/the_nilfs.c:795
     nilfs_segctor_destroy fs/nilfs2/segment.c:2749 [inline]
     nilfs_detach_log_writer+0x3fa/0x570 fs/nilfs2/segment.c:2812
     nilfs_put_super+0x2f/0xf0 fs/nilfs2/super.c:467
     generic_shutdown_super+0xcd/0x1f0 fs/super.c:464
     kill_block_super+0x4a/0x90 fs/super.c:1446
     deactivate_locked_super+0x6a/0xb0 fs/super.c:335
     deactivate_super+0x85/0x90 fs/super.c:366
     cleanup_mnt+0x277/0x2e0 fs/namespace.c:1118
     __cleanup_mnt+0x15/0x20 fs/namespace.c:1125
     task_work_run+0x8e/0x110 kernel/task_work.c:151
     tracehook_notify_resume include/linux/tracehook.h:188 [inline]
     exit_to_user_mode_loop kernel/entry/common.c:164 [inline]
     exit_to_user_mode_prepare+0x13c/0x170 kernel/entry/common.c:191
     syscall_exit_to_user_mode+0x16/0x30 kernel/entry/common.c:266
     do_syscall_64+0x45/0x80 arch/x86/entry/common.c:56
     entry_SYSCALL_64_after_hwframe+0x44/0xa9

There is no reproduction program, and the above is only theoretical
analysis.

Link: https://lkml.kernel.org/r/1629859428-5906-1-git-send-email-konishi.ryusuke@gmail.com
Fixes: ba65ae4729 ("nilfs2: add checkpoint tree to nilfs object")
Link: https://lkml.kernel.org/r/20210723012317.4146-1-thunder.leizhen@huawei.com
Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
 		2021-09-26 14:07:09 +02:00
..
9p 9P: Cast to loff_t before multiplying 2020-11-05 11:43:34 +01:00
adfs Merge branch 'work.adfs' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2019-07-19 11:33:22 -07:00
affs fs/affs: release old buffer head on error path 2021-03-04 10:26:48 +01:00
afs afs: Fix tracepoint string placement with built-in AFS 2021-07-28 13:30:58 +02:00
autofs autofs: fix a leak in autofs_expire_indirect() 2019-10-25 00:03:11 -04:00
befs fs: Fill in max and min timestamps in superblock 2019-08-30 07:27:17 -07:00
bfs bfs: don't use WARNING: string when it's just info. 2021-01-06 14:48:39 +01:00
btrfs btrfs: fix upper limit for max_inline for page size 64K 2021-09-22 12:26:38 +02:00
cachefiles cachefiles: Handle readpage error correctly 2020-11-05 11:43:36 +01:00
ceph ceph: take snap_empty_lock atomically with snaprealm refcount change 2021-08-18 08:57:04 +02:00
cifs cifs: fix wrong release in sess_alloc_buffer() failed path 2021-09-22 12:26:35 +02:00
coda y2038: add inode timestamp clamping 2019-09-19 09:42:37 -07:00
configfs configfs: fix memleak in configfs_release_bin_file 2021-07-14 16:53:46 +02:00
cramfs cramfs: fix usage on non-MTD device 2019-11-23 21:44:49 -05:00
crypto fscrypt: add fscrypt_symlink_getattr() for computing st_size 2021-09-12 08:56:38 +02:00
debugfs debugfs: Return error during {full/open}_proxy_open() on rmmod 2021-09-15 09:47:33 +02:00
devpts devpts_pty_kill(): don't bother with d_delete() 2019-09-03 09:30:56 -04:00
dlm fs: dlm: fix memory leak when fenced 2021-07-14 16:53:17 +02:00
ecryptfs Revert "ecryptfs: replace BUG_ON with error handling code" 2021-05-26 12:05:19 +02:00
efivarfs efivarfs: revert "fix memory leak in efivarfs_create()" 2020-12-02 08:49:53 +01:00
efs fs: Fill in max and min timestamps in superblock 2019-08-30 07:27:17 -07:00
erofs erofs: add unsupported inode i_format check 2021-05-11 14:04:02 +02:00
exportfs exportfs_decode_fh(): negative pinned may become positive without the parent locked 2019-11-10 11:56:05 -05:00
ext2 ext2: don't update mtime on COW faults 2020-09-09 19:12:30 +02:00
ext4 ext4: report correct st_size for encrypted symlinks 2021-09-12 08:56:38 +02:00
f2fs f2fs: fix to unmap pages from userspace process in punch_hole() 2021-09-22 12:26:26 +02:00
fat fat: don't allow to mount if the FAT length == 0 2020-06-17 16:40:36 +02:00
freevxfs fs: Fill in max and min timestamps in superblock 2019-08-30 07:27:17 -07:00
fscache fscache: Fix cookie key hashing 2021-09-22 12:26:25 +02:00
fuse fuse: fix use after free in fuse_read_interrupt() 2021-09-22 12:26:43 +02:00
gfs2 gfs2: Don't call dlm after protocol is unmounted 2021-09-22 12:26:33 +02:00
hfs hfs: add lock nesting notation to hfs_find_init 2021-07-31 08:19:38 +02:00
hfsplus hfsplus: prevent corruption in shrinking truncate 2021-05-19 10:08:29 +02:00
hostfs hostfs: fix memory handling in follow_link() 2021-04-14 08:24:14 +02:00
hpfs fs: hpfs: Initialize filesystem timestamp ranges 2019-08-30 08:11:25 -07:00
hugetlbfs hugetlbfs: fix mount mode command line processing 2021-07-28 13:31:01 +02:00
iomap mm/swap: consider max pages in iomap_swapfile_add_extent 2021-09-15 09:47:35 +02:00
isofs isofs: joliet: Fix iocharset=utf8 mount option 2021-09-15 09:47:27 +02:00
jbd2 jbd2: fix up sparse warnings in checkpoint code 2020-11-18 19:20:30 +01:00
jffs2 jffs2: check the validity of dstlen in jffs2_zlib_compress() 2021-05-11 14:04:16 +02:00
jfs fs/jfs: Fix missing error code in lmLogInit() 2021-07-20 16:10:42 +02:00
kernfs kernfs: do not call fsnotify() with name without a parent 2020-08-19 08:16:12 +02:00
lockd lockd: lockd server-side shouldn't set fl_ops 2021-09-22 12:26:34 +02:00
minix fs/minix: remove expected error message in block_to_path() 2020-08-21 13:05:37 +02:00
nfs NFSv4/pNFS: Don't call _nfs4_pnfs_v3_ds_connect multiple times 2021-07-20 16:10:50 +02:00
nfs_common nfs_common: need lock during iterate through the list 2020-12-30 11:51:22 +01:00
nfsd nfsd4: Fix forced-expiry locking 2021-09-15 09:47:35 +02:00
nilfs2 nilfs2: use refcount_dec_and_lock() to fix potential UAF 2021-09-26 14:07:09 +02:00
nls treewide: Add SPDX license identifier - Makefile/Kconfig 2019-05-21 10:50:46 +02:00
notify fanotify: fix ignore mask logic for events on child and on dir 2020-06-17 16:40:24 +02:00
ntfs ntfs: fix validity check for file name attribute 2021-07-14 16:53:01 +02:00
ocfs2 ocfs2: issue zeroout to EOF blocks 2021-08-04 12:27:37 +02:00
omfs fs: omfs: Initialize filesystem timestamp ranges 2019-08-30 08:11:25 -07:00
openpromfs Merge branch 'work.mount0' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2019-07-19 10:42:02 -07:00
orangefs orangefs: fix orangefs df output. 2021-07-20 16:10:48 +02:00
overlayfs ovl: fix BUG_ON() in may_delete() when called from ovl_cleanup() 2021-09-22 12:26:37 +02:00
proc mm, oom: make the calculation of oom badness more accurate 2021-09-03 10:08:12 +02:00
pstore pstore: Fix typo in compression option name 2021-03-04 10:26:45 +01:00
qnx4 fs: Fill in max and min timestamps in superblock 2019-08-30 07:27:17 -07:00
qnx6 fs: Fill in max and min timestamps in superblock 2019-08-30 07:27:17 -07:00
quota quota: Fix memory leak when handling corrupted quota file 2021-03-04 10:26:26 +01:00
ramfs ramfs: fix nommu mmap with gaps in the page cache 2020-10-29 09:57:53 +01:00
reiserfs reiserfs: check directory items on read from disk 2021-08-12 13:21:05 +02:00
romfs romfs: fix uninitialized memory leak in romfs_dev_read() 2020-08-26 10:40:51 +02:00
squashfs squashfs: fix divide error in calculate_skip() 2021-05-19 10:08:29 +02:00
sysfs sysfs: Add sysfs_emit and sysfs_emit_at to format sysfs output 2021-03-07 12:20:48 +01:00
sysv fs: sysv: Initialize filesystem timestamp ranges 2019-08-30 07:27:18 -07:00
tracefs tracing: Do not create tracefs files if tracefs lockdown is in effect 2019-10-12 20:49:07 -04:00
ubifs ubifs: report correct st_size for encrypted symlinks 2021-09-12 08:56:39 +02:00
udf udf_get_extendedattr() had no boundary checks. 2021-09-15 09:47:28 +02:00
ufs fs/ufs: avoid potential u32 multiplication overflow 2020-08-21 13:05:37 +02:00
unicode unicode: make array 'token' static const, makes object smaller 2019-09-17 11:48:24 -04:00
verity fs-verity: support builtin file signatures 2019-08-12 19:33:50 -07:00
xfs xfs: Fix assert failure in xfs_setattr_size() 2021-03-07 12:20:42 +01:00
Kconfig fs-verity for 5.4 2019-09-18 16:59:14 -07:00
Kconfig.binfmt binfmt_flat: make support for old format binaries optional 2019-06-24 09:16:47 +10:00
Makefile fs-verity for 5.4 2019-09-18 16:59:14 -07:00
aio.c aio: fix async fsync creds 2020-06-17 16:40:24 +02:00
anon_inodes.c Merge branch 'work.mount0' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2019-07-19 10:42:02 -07:00
attr.c utimes: Clamp the timestamps in notify_change() 2020-02-11 04:35:12 -08:00
bad_inode.c
…
binfmt_aout.c treewide: Add SPDX license identifier for more missed files 2019-05-21 10:50:45 +02:00
binfmt_elf.c fs/binfmt_elf.c: allocate initialized memory in fill_thread_core_info() 2020-06-03 08:21:27 +02:00
binfmt_elf_fdpic.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
binfmt_em86.c treewide: Add SPDX license identifier for more missed files 2019-05-21 10:50:45 +02:00
binfmt_flat.c binfmt_flat: revert "binfmt_flat: don't offset the data start" 2020-09-03 11:26:39 +02:00
binfmt_misc.c binfmt_misc: fix possible deadlock in bm_register_write 2021-03-17 17:03:57 +01:00
binfmt_script.c treewide: Add SPDX license identifier for more missed files 2019-05-21 10:50:45 +02:00
block_dev.c block: reexpand iov_iter after read/write 2021-05-22 11:38:29 +02:00
buffer.c fs: Don't invalidate page buffers in block_write_full_page() 2020-11-05 11:43:24 +01:00
char_dev.c chardev: Avoid potential use-after-free in 'chrdev_open()' 2020-01-14 20:08:18 +01:00
compat.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
compat_binfmt_elf.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 193 2019-05-30 11:29:21 -07:00
compat_ioctl.c fix compat handling of FICLONERANGE, FIDEDUPERANGE and FS_IOC_FIEMAP 2020-01-09 10:20:05 +01:00
coredump.c coredump: fix core_pattern parse error 2020-12-11 13:23:30 +01:00
d_path.c fs: fix NULL dereference due to data race in prepend_path() 2020-10-29 09:57:45 +01:00
dax.c dax: fix ENOMEM handling in grab_mapping_entry() 2021-07-14 16:53:25 +02:00
dcache.c fix dget_parent() fastpath race 2020-10-01 13:17:19 +02:00
dcookies.c treewide: Add SPDX license identifier for missed files 2019-05-21 10:50:45 +02:00
direct-io.c fs: direct-io: fix missing sdio->boundary 2021-04-14 08:24:11 +02:00
drop_caches.c fs: avoid softlockups in s_inodes iterators 2020-01-12 12:21:37 +01:00
eventfd.c eventfd: track eventfd_signal() recursion depth 2020-02-11 04:35:37 -08:00
eventpoll.c ep_create_wakeup_source(): dentry name can change under you... 2020-10-07 08:01:31 +02:00
exec.c exec: Transform exec_update_mutex into a rw_semaphore 2021-01-09 13:44:55 +01:00
fcntl.c fcntl: fix potential deadlock for &fasync_struct.fa_lock 2021-09-15 09:47:28 +02:00
fhandle.c fs/handle.c - fix up kerneldoc 2019-08-07 21:51:47 -04:00
file.c fix multiplication overflow in copy_fdtable() 2020-05-27 17:46:12 +02:00
file_table.c vfs: Export flush_delayed_fput for use by knfsd. 2019-08-19 11:00:39 -04:00
filesystems.c fs/filesystems.c: downgrade user-reachable WARN_ONCE() to pr_warn_once() 2020-04-17 10:50:21 +02:00
fs-writeback.c writeback: fix obtain a reference to a freeing memcg css 2021-07-14 16:53:35 +02:00
fs_context.c vfs: subtype handling moved to fuse 2019-09-06 21:28:49 +02:00
fs_parser.c vfs: Make fs_parse() handle fs_param_is_fd-type params better 2019-09-12 21:06:14 -04:00
fs_pin.c switch the remnants of releasing the mountpoint away from fs_pin 2019-07-16 22:52:37 -04:00
fs_struct.c treewide: Add SPDX license identifier for missed files 2019-05-21 10:50:45 +02:00
fs_types.c
…
fsopen.c Merge branch 'work.mount0' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2019-07-19 10:42:02 -07:00
inode.c futex: Fix inode life-time issue 2020-03-25 08:25:58 +01:00
internal.h cgroup1: fix leaked context root causing sporadic NULL deref in LTP 2021-07-31 08:19:37 +02:00
io_uring.c io_uring: Fix current->fs handling in io_sq_wq_submit_work() 2021-01-30 13:54:10 +01:00
ioctl.c compat_ioctl: add compat_ptr_ioctl() 2019-12-17 19:55:30 +01:00
libfs.c libfs: fix error cast of negative value in simple_attr_write() 2020-11-24 13:29:19 +01:00
locks.c locks: reinstate locks_delete_block optimization 2020-03-25 08:25:41 +01:00
mbcache.c treewide: Add SPDX license identifier for more missed files 2019-05-21 10:50:45 +02:00
mount.h switch the remnants of releasing the mountpoint away from fs_pin 2019-07-16 22:52:37 -04:00
mpage.c fs: move guard_bio_eod() after bio_set_op_attrs 2020-01-17 19:48:21 +01:00
namei.c namei: only return -ECHILD from follow_dotdot_rcu() 2020-03-05 16:43:48 +01:00
namespace.c fs: warn about impending deprecation of mandatory locks 2021-08-26 08:36:22 -04:00
no-block.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
nsfs.c vfs: Convert nsfs to use the new mount API 2019-05-25 18:00:06 -04:00
open.c cifs_atomic_open(): fix double-put on late allocation failure 2020-03-18 07:17:51 +01:00
pipe.c pipe: increase minimum default pipe size to 2 pages 2021-08-12 13:21:02 +02:00
pnode.c propagate_one(): mnt_set_mountpoint() needs mount_lock 2020-05-02 08:48:44 +02:00
pnode.h mount: fix mounting of detached mounts onto targets that reside on shared mounts 2021-03-17 17:03:33 +01:00
posix_acl.c treewide: Add SPDX license identifier for missed files 2019-05-21 10:50:45 +02:00
proc_namespace.c vfs: subtype handling moved to fuse 2019-09-06 21:28:49 +02:00
read_write.c fs: allow deduplication of eof block into the end of the destination file 2020-02-11 04:35:23 -08:00
readdir.c readdir: make sure to verify directory entry for legacy interfaces too 2021-04-21 12:56:16 +02:00
select.c kernel, fs: Introduce and use set_restart_fn() and arch_set_restart_data() 2021-03-24 11:26:44 +01:00
seq_file.c seq_file: disallow extremely large seq buffer allocations 2021-07-20 16:10:54 +02:00
signalfd.c fs/signalfd.c: fix inconsistent return codes for signalfd4 2020-08-26 10:40:58 +02:00
splice.c splice: only read in as much information as there is pipe buffer space 2019-12-17 19:56:52 +01:00
stack.c treewide: Add SPDX license identifier for missed files 2019-05-21 10:50:45 +02:00
stat.c
…
statfs.c vfs: Fix EOVERFLOW testing in put_compat_statfs64 2019-10-03 14:21:35 -07:00
super.c vfs: remove lockdep bogosity in __sb_start_write 2020-11-24 13:29:01 +01:00
sync.c
…
timerfd.c timerfd: Prepare for PREEMPT_RT 2019-08-01 20:51:23 +02:00
userfaultfd.c userfaultfd: prevent concurrent API initialization 2021-09-22 12:26:26 +02:00
utimes.c utimes: Clamp the timestamps in notify_change() 2020-02-11 04:35:12 -08:00
xattr.c xattr: break delegations in {set,remove}xattr 2020-08-11 15:33:39 +02:00