Re: How to keep the kernel from crashing on cd9660 error ?

["J. Hannken-Illjes" <hannken%eis.cs.tu-bs.de@localhost>]

On 03 Jun 2014, at 18:31, Thomas Schmitt <scdbackup%gmx.net@localhost> wrote:

> Hi,
> 
> i could need advise about getnewvnode(9) and how to revoke
> the creation of the vnode.
> 
> While testing my next change proposal for stability with
> undigestible ISO 9660 files, i experienced kernel crashes which
> look like memory corruption.
> 
> To prove that my changes are not to blame, i installed a little
> error generator in the current cd9660_vfsops.c, at the place
> where my new code will throw EOPNOTSUPP because of an undigestible
> file.

EOPNOTSUPP doesn't look right here ...

> It triggers the same crash as the real error complaint in my
> changed code. So the problem already sits in cd9660.
> 
> I could possibly fake an ISO image which would trigger an error
> condition that is already in function cd9660_vget_internal() and
> very near to the spot where my test causes havoc.
> 
> So this could be a DoS attack path.
<snip>

The upcoming conversion to vcache should make it easier to deal with
these problems.  I will add some priority to the conversion of cd9660.

--
J. Hannken-Illjes - hannken%eis.cs.tu-bs.de@localhost - TU Braunschweig 
(Germany)