[PATCH v2 1/3] posix: Remove dynamic memory allocation from execl{e,p}

[Adhemerval Zanella]

On 01-02-2016 14:52, Joseph Myers wrote:
> On Mon, 1 Feb 2016, Adhemerval Zanella wrote:
> 
>> +  char *argv[argc+1];
>> +  va_start (ap, arg);
>> +  argv[0] = (char*) arg;
>> +  for (i = 1; i < argc; i++)
>> +     argv[i] = va_arg (ap, char *);
>> +  argv[i] = NULL;
> 
> I don't see how you're ensuring this stack allocation is safe (i.e. if 
> it's too big, it doesn't corrupt memory that's in use by other threads).  
> Can't it jump beyond any guard page and start overwriting other memory, 
> possibly in use by another thread, before reaching unmapped memory?  I'd 
> expect safe large stack allocations (as with -fstack-check) to need to 
> touch the pages in the right order (and doing that safely probably means 
> using -fstack-check).
> 

Right, it is not ensuring the safeness. Is '-fstack-check' the suffice 
option to ensure it or do we need a more strict one?