Re: CVE request: kernel: proc: clean up and fix /proc/<pid>/mem handling

["Jason A. Donenfeld" <Jason () zx2c4 com>]

On Sun, Jan 22, 2012 at 20:43, Solar Designer <solar () openwall com> wrote:
> On Sun, Jan 22, 2012 at 07:30:53PM +0100, Jason A. Donenfeld wrote:
> > The issue is described in detail here: http://blog.zx2c4.com/749
>
> Thanks!  This explains the self_exec_id issue and one attack on it.
>
> Why are you not posting this to oss-security yet?  Do you feel that your
> blog receives less exposure and you don't want to expose this additional
> detail on the attack to a wider audience until there are distro vendor
> updates?

No, I just didn't want to blog-spam a rather well focused mailing list
:-). I'll cc oss-security on this email though.


> BTW, self_exec_id was originally introduced into the kernel 10+ years
> ago with some involvement from me, and for a significantly different
> purpose (protecting changed parent against malicious child death signals).
> I think its use for /proc/pid/mem was introduced last year (2011).
>
> Any comments on the fix?
>
> > > > http://git.kernel.org/linus/e268337dfe26dfc7efd422a804dbb27977a3cccc
>
> My primary concern was that the first might be broken.  I have some
> further thoughts on this since I posted, though.  I'll post an update.

I'm not sure yet; I haven't looked at it carefully. First instinct is
that there's
[ old process { old & new ] new process}
overlapping as a possibility, but I really have no idea. I'll take a
closer look soon.

> Alexander