[PATCH v2 2/2] nss: Protect against errno changes in function lookup (bug 28953)

[Florian Weimer]

* Andreas Schwab:

> On Mär 10 2022, Florian Weimer via Libc-alpha wrote:
>
>> diff --git a/nss/nss_module.c b/nss/nss_module.c
>> index f9a1263e5a..4839448e35 100644
>> --- a/nss/nss_module.c
>> +++ b/nss/nss_module.c
>> @@ -330,9 +330,14 @@ name_search (const void *left, const void *right)
>>  void *
>>  __nss_module_get_function (struct nss_module *module, const char *name)
>>  {
>> +  /* A successful dlopen might clobber errno.   */
>> +  int saved_errno = errno;
>> +
>>    if (!__nss_module_load (module))
>>      return NULL;
>>  
>> +  __set_errno (saved_errno);
>> +
>
> Is an unsuccessful load allowed to change errno?

This is bug 22041 territory.  I think in the current code, we should not
change errno here.  Good catch.  I'll send a v3.

Thanks,
Florian