[oss-security] lockdown bypass on mainline kernel for loading unsigned modules

[Jann Horn]

On Mon, Jun 15, 2020 at 6:24 PM John Haxby <john.haxby at oracle.com> wrote:
> > On 15 Jun 2020, at 11:26, Jason A. Donenfeld <Jason at zx2c4.com> wrote:
> > Yesterday, I found a lockdown bypass in Ubuntu 18.04's kernel using
> > ACPI table tricks via the efi ssdt variable [1]. Today I found another
> > one that's a bit easier to exploit and appears to be unpatched on
> > mainline, using acpi_configfs to inject an ACPI table. The tricks are
> > basically the same as the first one, but this one appears to be
> > unpatched, at least on my test machine. Explanation is in the header
> > of the PoC:
> >
> > https://git.zx2c4.com/american-unsigned-language/tree/american-unsigned-language-2.sh
> >
> > I need to get some sleep, but if nobody posts a patch in the
> > meanwhile, I'll try to post a fix tomorrow.
> >
> > Jason
> >
> > [1] https://www.openwall.com/lists/oss-security/2020/06/14/1
>
>
> This looks CVE-worthy.   Are you going to ask for a CVE for it?

Does it really make sense to dole out CVEs for individual lockdown
bypasses when various areas of the kernel (such as filesystems and
BPF) don't see root->kernel privilege escalation issues as a problem?
It's not like applying the fix for this one issue is going to make
systems meaningfully safer.