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

[Adhemerval Zanella <adhemerval.zanella@linaro.org>]

On 18/01/2022 10:33, Adhemerval Zanella wrote:
> 
> 
> 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.

Yes, it is correct.  I will remove the 'l_auditing' field.