Read-only data in ELF libraries may be remapped writable at runtime (upcoming NDSS'17 paper)

[Florian Weimer]

On 12/23/2016 07:04 PM, Mathias Payer wrote:

> At the linker level you likely don't know if the referenced symbol is RO
> or not (as it could come from any object) -- only the runtime loader has
> this knowledge and at that time it is too late as PIE uses relative
> addressing inside the object.

The static linker necessarily sees a definition, otherwise it cannot 
produce a copy relocation because copy relocations must refer to objects 
of known size.

>>> PS: The C++ example code inf figure 4(a) has a typo, the call to the method
>>> b2 should probably be to b1.
>
> Can you be more specific? I don't see a call to b2 in Fig. 4a

I meant a2.

Thanks,
Florian