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Re: RFC: Shadow Stack support in glibc
On 09/06/17 12:40, H.J. Lu wrote:
> On Fri, Jun 9, 2017 at 4:32 AM, Florian Weimer <fweimer@redhat.com> wrote:
>> On 06/09/2017 01:28 PM, H.J. Lu wrote:
>>> Yes, 99% of codes just need to recompile. If context functions
>>> are used or jmpbuf is used independently of setjmp/longjmp,
>>> enabling is needed.
>>
>> Would you please clarify if the size of the type jmp_buf changes in the
>> new compilation mode?
>>
>
> jmp_buf size will be increased unconditionally in glibc whose <setjmp.h>
> has
>
> #if shadow stack is enabled
> asm ("Turn on shadow stack in program property"):
> #endif
>
> The old setjmp/longjuimp only use the old jmp_buf size and the new
> setjmp/longjuimp use the new jmp_buf size. The new setjmp/longjmp
> are used only if all input object files have shadow stack enabled in
> program property.
>
what happens if a process with shadow stack enabled
dlopens a lib with shadow stack disabled?