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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
arch RISC-V Fixes for 5.12-rc6 2021-04-03 11:52:18 -07:00
block block: remove the unused RQF_ALLOCED flag 2021-04-02 11:18:31 -06:00
certs certs: Replace K{U,G}IDT_INIT() with GLOBAL_ROOT_{U,G}ID 2021-01-21 16:16:10 +00:00
crypto crypto: mips/poly1305 - enable for all MIPS processors 2021-03-08 11:52:17 +01:00
Documentation ovl: restrict lower null uuid for "xino=auto" 2021-04-12 12:00:36 +02:00
drivers firewire: nosy: Fix a use-after-free bug in nosy_ioctl() 2021-04-04 14:05:45 -07:00
fs ovl: fix leaked dentry 2021-04-12 12:00:36 +02:00
include Char/Misc driver fixes for 5.12-rc6 2021-04-03 10:05:16 -07:00
init Merge branch 'akpm' (patches from Andrew) 2021-03-14 12:23:34 -07:00
ipc fs: make helpers idmap mount aware 2021-01-24 14:27:20 +01:00
kernel Fix stack trace entry size to stop showing garbage 2021-04-02 08:39:00 -07:00
lib XArray: Fix splitting to non-zero orders 2021-03-30 13:42:33 -04:00
LICENSES LICENSES: Add the CC-BY-4.0 license 2020-12-08 10:33:27 -07:00
mm mm: fix race by making init_zero_pfn() early_initcall 2021-03-30 09:46:12 -07:00
net Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2021-03-24 18:16:04 -07:00
samples Merge git://git.kernel.org:/pub/scm/linux/kernel/git/netdev/net 2021-03-09 17:15:56 -08:00
scripts kbuild: lto: Merge module sections if and only if CONFIG_LTO_CLANG is enabled 2021-04-01 14:15:59 -07:00
security tomoyo: don't special case PF_IO_WORKER for PF_KTHREAD 2021-03-28 13:11:29 +09:00
sound sound fixes for 5.12-rc6 2021-04-01 10:09:31 -07:00
tools x86: 2021-04-01 12:42:55 -07:00
usr Kbuild updates for v5.12 2021-02-25 10:17:31 -08:00
virt KVM: x86/mmu: Consider the hva in mmu_notifier retry 2021-02-22 13:16:53 -05:00
.clang-format cxl for 5.12 2021-02-24 09:38:36 -08:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore clang-lto series for v5.12-rc1 2021-02-23 09:28:51 -08:00
.mailmap Merge branch 'akpm' (patches from Andrew) 2021-03-25 11:43:43 -07:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS treewide: Miguel has moved 2021-02-26 09:41:03 -08:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS Char/Misc driver fixes for 5.12-rc6 2021-04-03 10:05:16 -07:00
Makefile Linux 5.12-rc6 2021-04-04 14:15:36 -07:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

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.