Re: rwx mapping between ex_table and rodata

[H. Peter Anvin]

Need to fix.  Not sure where the rwx mapping comes from.

On September 28, 2015 3:05:33 PM PDT, Kees Cook <keescook@xxxxxxxxxxxx> wrote:
>On Mon, Sep 28, 2015 at 2:16 PM, H. Peter Anvin <hpa@xxxxxxxxx> wrote:
>> On 09/25/2015 12:22 AM, Ingo Molnar wrote:
>>>>
>>>> To me it looks like another alignment/padding issue like got fixed
>>>> before. The space between __ex_table and rodata is (seems?) unused,
>so
>>>> the default page table permissions end up being W+X. Can we fix the
>>>> default to be NX instead? It'll make these bugs stay gone.
>>>
>>> Yeah. Wanna send a patch for that?
>>>
>>
>> At least in the high mapping space, the default should be no
>permissions
>> (not present), rather than just NX.
>
>Do you mean "should be" as in, that's how it's coded now, or "should
>be" in that we need to fix it? (If we need to fix it, where is that
>"default"? I haven't been able to find it yet.)
>
>-Kees

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