userns: limit the maximum depth of user_namespace->parent chain
authorOleg Nesterov <oleg@redhat.com>
Thu, 8 Aug 2013 16:55:32 +0000 (18:55 +0200)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Mon, 12 Aug 2013 01:35:25 +0000 (18:35 -0700)
commit5c5f9cd2b539879c4291fa24773795314e777354
treefcda00e4125fa6c70a067e87ad08bab634c1996f
parentc98ebcb618645d40cfec14b0534ff32126c114ce
userns: limit the maximum depth of user_namespace->parent chain

commit 8742f229b635bf1c1c84a3dfe5e47c814c20b5c8 upstream.

Ensure that user_namespace->parent chain can't grow too much.
Currently we use the hardroded 32 as limit.

Reported-by: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
include/linux/user_namespace.h
kernel/user_namespace.c