Re: [PATCH 1/5] elf: Fix audit regression

[Florian Weimer <fweimer@redhat.com>]

* Andreas Schwab:

> On Jul 07 2021, Adhemerval Zanella via Libc-alpha wrote:
>
>> @@ -771,7 +771,7 @@ dl_open_worker (void *a)
>>      {
>>        struct link_map *libc_map = GL(dl_ns)[args->nsid].libc_map;
>>  #ifdef SHARED
>> -      bool initial = libc_map->l_ns == LM_ID_BASE;
>> +      bool initial = libc_map != NULL ? libc_map->l_ns == LM_ID_BASE : false;
>
>          bool initial = libc_map != NULL && libc_map->l_ns == LM_ID_BASE;

True … but:

This is only used by dlopen/dlmopen, right?  And even if dlmopen is
called from an auditor (to load another libc), it is *never* the initial
libc in the base namespace.

The actual base namespace libc is handled in elf/rtld.c:dl_main:

  /* Relocation is complete.  Perform early libc initialization.  This
     is the initial libc, even if audit modules have been loaded with
     other libcs.  */
  _dl_call_libc_early_init (GL(dl_ns)[LM_ID_BASE].libc_map, true);

And I think the dl_open_worker should mirror that and just do:

  if (!args->libc_already_loaded)
    /* This is never the initial libc because it has been loaded via
       dlmopen.  */
    _dl_call_libc_early_init (libc_map, false);

Thanks,
Florian