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On 18.05.2012 09:18, Matthew Thode wrote:
> On 05/17/2012 01:42 PM, RB wrote:
>> On Thu, May 17, 2012 at 6:04 AM, Anthony G. Basile 
>> <[email protected]> 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.
>> 
>> It took less time to work it out than I expected; a bit of a
>> binary search through the grsecurity/PaX options I had enabled
>> pretty clearly indicates the culprint is PAX_MEMORY_UDEREF.
>> Using both xf86-video-intel-2.17.0-r3 and 2.19.0 and
>> xorg-server-1.11.3 and 1.12.1, there's a bug introduced between
>> hardened-sources-3.2.2-r1 and
>>> =3.2.11 that by enabling PAX_MEMORY_UDEREF the i915/i965
>>> kernel
>> module gets a "BUG: unable to handle kernel NULL pointer
>> dereference" in i915_gem_execbuffer_reserve when starting X.
>> 
>> I'll submit a bug shortly.
>> 
> must be why I never hit it (I enable kernexec but leave uderef
> disabled for virt).
> 

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)

WKR
Hinnerk


PS: Issuing grep -i pax on my .config I get:

# PaX
CONFIG_PAX_KERNEXEC_PLUGIN=y
CONFIG_PAX_PER_CPU_PGD=y
CONFIG_PAX=y
# PaX Control
# CONFIG_PAX_SOFTMODE is not set
CONFIG_PAX_EI_PAX=y
CONFIG_PAX_PT_PAX_FLAGS=y
CONFIG_PAX_XATTR_PAX_FLAGS=y
# CONFIG_PAX_NO_ACL_FLAGS is not set
CONFIG_PAX_HAVE_ACL_FLAGS=y
# CONFIG_PAX_HOOK_ACL_FLAGS is not set
CONFIG_PAX_NOEXEC=y
CONFIG_PAX_PAGEEXEC=y
# CONFIG_PAX_EMUTRAMP is not set
CONFIG_PAX_MPROTECT=y
# CONFIG_PAX_MPROTECT_COMPAT is not set
# CONFIG_PAX_ELFRELOCS is not set
CONFIG_PAX_KERNEXEC=y
CONFIG_PAX_KERNEXEC_PLUGIN_METHOD_BTS=y
CONFIG_PAX_KERNEXEC_PLUGIN_METHOD="bts"
CONFIG_PAX_ASLR=y
CONFIG_PAX_RANDKSTACK=y
CONFIG_PAX_RANDUSTACK=y
CONFIG_PAX_RANDMMAP=y
CONFIG_PAX_MEMORY_STACKLEAK=y
CONFIG_PAX_MEMORY_UDEREF=y
CONFIG_PAX_REFCOUNT=y
CONFIG_PAX_USERCOPY=y
# CONFIG_PAX_SIZE_OVERFLOW is not set




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