linux-kernel - [patch] fs: umount on symlinlk leaks mnt count

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [day] [month] [year] [list]

Date:	Sun, 20 Jul 2014 09:47:58 +0400
From:	Vasily Averin <vvs@...allels.com>
To:	Alexander Viro <viro@...iv.linux.org.uk>,
	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [patch] fs: umount on symlinlk leaks mnt count

Currently umount on symlink blocks following umount:

/vz is separate mount

# ls /vz/ -al | grep test
drwxr-xr-x.  2 root root       4096 Jul 19 01:14 testdir
lrwxrwxrwx.  1 root root         11 Jul 19 01:16 testlink -> /vz/testdir

# umount -l /vz/testlink
umount: /vz/testlink: not mounted (expected)

# lsof /vz
# umount /vz
umount: /vz: device is busy. (unexpected)

Looks like an extra refcount on mnt was taken in mountpoint_last()
Patch below fixes the problem on my test node.

Signed-off-by:	Vasily Averin <vvs@...nvz.org>

View attachment "diff-umount-symlink-ms" of type "text/plain" (328 bytes)