[RFC v2] elf: Extend glibc.rtld.execstack tunable to force executable stack (BZ 32653)

[Adhemerval Zanella Netto]

On 11/02/25 05:12, Florian Weimer wrote:
> * Adhemerval Zanella:
> 
>> diff --git a/csu/libc-start.c b/csu/libc-start.c
>> index 6f3d52e223..7a13961b18 100644
>> --- a/csu/libc-start.c
>> +++ b/csu/libc-start.c
>> @@ -307,6 +307,9 @@ LIBC_START_MAIN (int (*main) (int, char **, char ** MAIN_AUXVEC_DECL),
>>  
>>  #endif /* !SHARED  */
>>  
>> +  /* Make the thread executable if required.  */
>> +  GLRO(dl_check_executable_stack) ();
> 
> This is really late.  Why can't this done from within ld.so?
> 
> We don't need this for static binaries.

I think we can, I moved this as late as possible so loader itself would
keep using a non-executable stack. I will send v2.

> 
> The tunable is the right approach.  I thought we had this already. 8->

We do have an option to avoid an executable-stack altogether.

> 
> Thanks,
> Florian
>