Bug#681418: #681418 debugfs is a big security hole

[Steve Cotton <steve@s.cotton.clara.co.uk>]

On Sun, May 05, 2013 at 12:24:44PM +0300, Timo Juhani Lindfors wrote:
> the issue still exists in experimental
> 
> lindi3:~$ ls -ld /sys/kernel/debug
> drwxr-xr-x 2 root root 0 May  5 12:02 /sys/kernel/debug
> lindi3:~$ cat /proc/version 
> Linux version 3.8-trunk-amd64 (debian-kernel@lists.debian.org) (gcc version 4.7.2 (Debian 4.7.2-5) ) #1 SMP Debian 3.8.5-1~experimental.1

Hi Timo,

For me the mount point changes permission when mounted, and from the hard link count I guess you have it unmounted.

tsunami:~# umount /sys/kernel/debug/
tsunami:~# ls -ld /sys/kernel/debug/
drwxr-xr-x 2 root root 0 Jul 30 13:08 /sys/kernel/debug/
tsunami:~# mount -t debugfs none /sys/kernel/debug
tsunami:~# ls -ld /sys/kernel/debug/
drwx------ 16 root root 0 Jul 29 08:52 /sys/kernel/debug/

I'm using a local build of 3.10.2.

Regards,
Steve