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SubjectRe: rwx mapping between ex_table and rodata

* Kees Cook <keescook@chromium.org> wrote:

> On Thu, Sep 24, 2015 at 1:26 PM, Stephen Smalley <sds@tycho.nsa.gov> wrote:
> > Hi,
> >
> > With the attached config and 4.3-rc2 on x86_64, I see the following in /sys/kernel/debug/kernel_page_tables:
> > ...
> > ---[ High Kernel Mapping ]---
> > 0xffffffff80000000-0xffffffff81000000 16M pmd
> > 0xffffffff81000000-0xffffffff81600000 6M ro PSE GLB x pmd
> > 0xffffffff81600000-0xffffffff81775000 1492K ro GLB x pte
> > 0xffffffff81775000-0xffffffff81800000 556K RW GLB x pte
> > ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Btw., I think we should run this lookup automatically in late bootup, if
CONFIG_X86_PTDUMP=y, and print a WARN()ing if there's any RWX permissions in the
mappings.

That makes sure automated testing picks new bugs up.

Thanks,

Ingo


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