[PATCH v10 2/4] elf: Fix initial-exec TLS access on audit modules (BZ #28096)

[Adhemerval Zanella]

On 18/01/2022 10:29, Florian Weimer wrote:
> * Adhemerval Zanella:
> 
>>>> So we need to avoid initialization only for the libc.so loading by
>>>> audit libraries, the default one should still be initialized (marked
>>>> as [INIT]).  Later when new threads are created we need to initialized
>>>> everything.
>>>
>>> That's what I tried to express with the LM_ID_BASE check.
>>
>> The problem is 'map->l_ns == LM_ID_BASE && !init_tls' will not initilize
>> the required libc.so for main application during audit module loading.
>> With tst-audit21:
>>
>>    1593586:     [rtld.c:965] load_audit_module
>>    1593586:     [rtld.c:972] load_audit_module
>>    1593586:     [rtld.c:2464] dl_main
>>    1593586:     [../elf/dl-tls.c:605] map->l_name= map->l_ns=0 map->l_auditing=0 init_tls=0
>>    1593586:     [../elf/dl-tls.c:610] map->l_name=[...]/elf/tst-auditmod21a.so map->l_ns=1 map->l_auditing=1 init_tls=0 [INIT]
>>    1593586:     [../elf/dl-tls.c:610] map->l_name=[...]/libc.so.6 map->l_ns=1 map->l_auditing=1 init_tls=0 [INIT]
>>    1593586:     [../elf/dl-tls.c:605] map->l_name=[...]/libc.so.6 map->l_ns=0 map->l_auditing=0 init_tls=0
>>    1593586:     [../elf/dl-tls.c:627]
>>    1593586:     [rtld.c:2466] dl_main
>> Segmentation fault (core dumped)
> 
> Looks like the condition is simply reversed?  [INIT] should only appear
> for map->l_ns == 0, right?

Hum, 'if (map->l_ns != LM_ID_BASE && !init_tls)' seems correct indeed.  
Let me run a full make check to certify it.