On Fri, May 18, 2012 at 2:11 AM, Hinnerk van Bruinehsen
<h.v.bruinehsen@fu-berlin.de> wrote:
> For me X works fine with UDEREF enabled. I'm using xorg-server-1.12.1
> and xf86-video-intel-2.19.0. (2 laptops, 1 core2 duo, 1 first
> generation i5, if that has got something to do with it)

That's because (as I just found by testing) PAX_KERNEXEC "mitigates"
the oops. To put it in something of a boolean form, the following
produces the crashes:

PAX_MEMORY_UDEREF && !(PAX_MEMORY_UDEREF && PAX_KERNEXEC)

On 18 May 2012 at 13:29, RB wrote:

> That's because (as I just found by testing) PAX_KERNEXEC "mitigates"
> the oops. To put it in something of a boolean form, the following
> produces the crashes:
>
> PAX_MEMORY_UDEREF && !(PAX_MEMORY_UDEREF && PAX_KERNEXEC)

do you have any slab debugging options enabled by any chance?

On Fri, May 18, 2012 at 4:18 PM, PaX Team <pageexec@freemail.hu> wrote:
>> PAX_MEMORY_UDEREF && !(PAX_MEMORY_UDEREF && PAX_KERNEXEC)
>
> do you have any slab debugging options enabled by any chance?

None intentionally, and none unintentionally that I can tell.
SLUB_DEBUG is on, but that's forced on by having SLUB as the
allocator. DEBUG_KERNEL is also on, but so I can enable TIMER_STATS
(for xfce4-power-manager).

On Thu, May 17, 2012 at 6:04 AM, Anthony G. Basile
<basile@opensource.dyc.edu> wrote:
> Please open a bug, attach both config files. *It would be useful if you also
> identify on which options it breaks. *Liberte, last I looked, has quite a
> few hardening features off. *Pay attention to GRKERNSEC_IO, PAX_PAGEEXEC,
> PAX_KERNEXEC, PAX_MEMORY_UDEREF.

Bugged, #416637. Only attached one .config since it's now clear
precisely what set of options creates this.