[PATCH 8/8] elf: Scrub and reseed the AT_RANDOM bytes after deriving the guards (BZ 34197)

[Adhemerval Zanella Netto]

On 11/06/26 17:25, DJ Delorie wrote:
> 
> Adhemerval Zanella Netto <adhemerval.zanella@linaro.org> writes:
>>>> -  _dl_random = NULL;
>>>> +  _dl_reseed_random (&_dl_random);
>>>
>>> can _dl_reseed_random ever be called twice in the same program?  This
>>> second one happens when we load audit modules, but you don't test that
>>> case, and I wonder if calling it twice might result in NULL guards, or
>>> mismatched ones...
>>
>> The security_init cannot be called twice: in dl_main, need_security_init is
>> set 'false' after the early audit-path call. The later call around line 2020
>> is gated on need_security_init, and the __libc_start_main's call is only for
>> !SHARED.
>>
>> But I think even if a double call were ever introduced, the function should be
>> safe. The if (*dl_random == NULL) return; early-return makes the second call a 
>> no-op.
> 
> I was more worried about the call in csu/libc-start.c and the call in
> elf/rtld.c both affecting the same process.
> 

Right, the csu/libc-start.c is only for static objects.  The static-dlopen edge
case also does trigger the elf/rtld.c initialization, and that's why we have
__rtld_static_init to handle the requires missing pieces.