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eaab1d45cd
linux/fs/overlayfs
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Mickaël Salaün eaab1d45cd ovl: fix leaked dentry 
Since commit 6815f479ca ("ovl: use only uppermetacopy state in
ovl_lookup()"), overlayfs doesn't put temporary dentry when there is a
metacopy error, which leads to dentry leaks when shutting down the related
superblock:

  overlayfs: refusing to follow metacopy origin for (/file0)
  ...
  BUG: Dentry (____ptrval____){i=3f33,n=file3}  still in use (1) [unmount of overlay overlay]
  ...
  WARNING: CPU: 1 PID: 432 at umount_check.cold+0x107/0x14d
  CPU: 1 PID: 432 Comm: unmount-overlay Not tainted 5.12.0-rc5 #1
  ...
  RIP: 0010:umount_check.cold+0x107/0x14d
  ...
  Call Trace:
   d_walk+0x28c/0x950
   ? dentry_lru_isolate+0x2b0/0x2b0
   ? __kasan_slab_free+0x12/0x20
   do_one_tree+0x33/0x60
   shrink_dcache_for_umount+0x78/0x1d0
   generic_shutdown_super+0x70/0x440
   kill_anon_super+0x3e/0x70
   deactivate_locked_super+0xc4/0x160
   deactivate_super+0xfa/0x140
   cleanup_mnt+0x22e/0x370
   __cleanup_mnt+0x1a/0x30
   task_work_run+0x139/0x210
   do_exit+0xb0c/0x2820
   ? __kasan_check_read+0x1d/0x30
   ? find_held_lock+0x35/0x160
   ? lock_release+0x1b6/0x660
   ? mm_update_next_owner+0xa20/0xa20
   ? reacquire_held_locks+0x3f0/0x3f0
   ? __sanitizer_cov_trace_const_cmp4+0x22/0x30
   do_group_exit+0x135/0x380
   __do_sys_exit_group.isra.0+0x20/0x20
   __x64_sys_exit_group+0x3c/0x50
   do_syscall_64+0x45/0x70
   entry_SYSCALL_64_after_hwframe+0x44/0xae
  ...
  VFS: Busy inodes after unmount of overlay. Self-destruct in 5 seconds.  Have a nice day...

This fix has been tested with a syzkaller reproducer.

Cc: Amir Goldstein <amir73il@gmail.com>
Cc: <stable@vger.kernel.org> # v5.8+
Reported-by: syzbot <syzkaller@googlegroups.com>
Fixes: 6815f479ca ("ovl: use only uppermetacopy state in ovl_lookup()")
Signed-off-by: Mickaël Salaün <mic@linux.microsoft.com>
Link: https://lore.kernel.org/r/20210329164907.2133175-1-mic@digikod.net
Reviewed-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2021-04-12 12:00:36 +02:00
..
copy_up.c idmapped-mounts-v5.12 2021-02-23 13:39:45 -08:00
dir.c idmapped-mounts-v5.12 2021-02-23 13:39:45 -08:00
export.c ovl: propagate ovl_fs to ovl_decode_real_fh and ovl_encode_real_fh 2020-11-12 11:31:55 +01:00
file.c ovl: plumb through flush method 2021-04-12 12:00:36 +02:00
inode.c idmapped-mounts-v5.12 2021-02-23 13:39:45 -08:00
Kconfig docs: fix broken references to text files 2020-04-20 15:35:59 -06:00
Makefile treewide: Add SPDX license identifier - Makefile/Kconfig 2019-05-21 10:50:46 +02:00
namei.c ovl: fix leaked dentry 2021-04-12 12:00:36 +02:00
overlayfs.h idmapped-mounts-v5.12 2021-02-23 13:39:45 -08:00
ovl_entry.h ovl: implement volatile-specific fsync error behaviour 2021-01-28 10:22:48 +01:00
readdir.c ovl: implement volatile-specific fsync error behaviour 2021-01-28 10:22:48 +01:00
super.c ovl: restrict lower null uuid for "xino=auto" 2021-04-12 12:00:36 +02:00
util.c idmapped-mounts-v5.12 2021-02-23 13:39:45 -08:00