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From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org
Cc: "Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
	stable@vger.kernel.org, "Amir Goldstein" <amir73il@gmail.com>,
	syzbot <syzkaller@googlegroups.com>,
	"Mickaël Salaün" <mic@linux.microsoft.com>,
	"Vivek Goyal" <vgoyal@redhat.com>,
	"Miklos Szeredi" <mszeredi@redhat.com>
Subject: [PATCH 5.12 08/17] ovl: fix leaked dentry
Date: Wed,  5 May 2021 14:06:03 +0200	[thread overview]
Message-ID: <20210505112325.225563588@linuxfoundation.org> (raw)
In-Reply-To: <20210505112324.956720416@linuxfoundation.org>

From: Mickaël Salaün <mic@linux.microsoft.com>

commit eaab1d45cdb4bb0c846bd23c3d666d5b90af7b41 upstream.

Since commit 6815f479ca90 ("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: 6815f479ca90 ("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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 fs/overlayfs/namei.c |    1 +
 1 file changed, 1 insertion(+)

--- a/fs/overlayfs/namei.c
+++ b/fs/overlayfs/namei.c
@@ -919,6 +919,7 @@ struct dentry *ovl_lookup(struct inode *
 			continue;
 
 		if ((uppermetacopy || d.metacopy) && !ofs->config.metacopy) {
+			dput(this);
 			err = -EPERM;
 			pr_warn_ratelimited("refusing to follow metacopy origin for (%pd2)\n", dentry);
 			goto out_put;



  parent reply	other threads:[~2021-05-05 12:10 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-05 12:05 [PATCH 5.12 00/17] 5.12.2-rc1 review Greg Kroah-Hartman
2021-05-05 12:05 ` [PATCH 5.12 01/17] mips: Do not include hi and lo in clobber list for R6 Greg Kroah-Hartman
2021-05-05 12:05 ` [PATCH 5.12 02/17] netfilter: conntrack: Make global sysctls readonly in non-init netns Greg Kroah-Hartman
2021-05-05 12:05 ` [PATCH 5.12 03/17] net: usb: ax88179_178a: initialize local variables before use Greg Kroah-Hartman
2021-05-05 12:05 ` [PATCH 5.12 04/17] drm/i915: Disable runtime power management during shutdown Greg Kroah-Hartman
2021-05-05 12:06 ` [PATCH 5.12 05/17] bpf: Fix masking negation logic upon negative dst register Greg Kroah-Hartman
2021-05-05 12:06 ` [PATCH 5.12 06/17] bpf: Fix leakage of uninitialized bpf stack under speculation Greg Kroah-Hartman
2021-05-05 12:06 ` [PATCH 5.12 07/17] net: qrtr: Avoid potential use after free in MHI send Greg Kroah-Hartman
2021-05-05 12:06 ` Greg Kroah-Hartman [this message]
2021-05-05 12:06 ` [PATCH 5.12 09/17] ovl: allow upperdir inside lowerdir Greg Kroah-Hartman
2021-05-05 12:06 ` [PATCH 5.12 10/17] ALSA: usb-audio: Add MIDI quirk for Vox ToneLab EX Greg Kroah-Hartman
2021-05-05 12:06 ` [PATCH 5.12 11/17] ALSA: usb-audio: Fix implicit sync clearance at stopping stream Greg Kroah-Hartman
2021-05-05 12:06 ` [PATCH 5.12 12/17] USB: Add LPM quirk for Lenovo ThinkPad USB-C Dock Gen2 Ethernet Greg Kroah-Hartman
2021-05-05 12:06 ` [PATCH 5.12 13/17] USB: Add reset-resume quirk for WD19s Realtek Hub Greg Kroah-Hartman
2021-05-05 12:06 ` [PATCH 5.12 14/17] ASoC: ak4458: Add MODULE_DEVICE_TABLE Greg Kroah-Hartman
2021-05-05 12:06 ` [PATCH 5.12 15/17] ASoC: ak5558: " Greg Kroah-Hartman
2021-05-05 12:06 ` [PATCH 5.12 16/17] platform/x86: thinkpad_acpi: Correct thermal sensor allocation Greg Kroah-Hartman
2021-05-05 12:06 ` [PATCH 5.12 17/17] perf/core: Fix unconditional security_locked_down() call Greg Kroah-Hartman
2021-05-05 17:52 ` [PATCH 5.12 00/17] 5.12.2-rc1 review Fox Chen
2021-05-05 19:09 ` Naresh Kamboju
2021-05-05 19:44 ` Florian Fainelli
2021-05-06  1:59 ` Guenter Roeck

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