Re: [PATCH] elf: Check objname before calling fatal_error

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

On 08/04/24 13:58, H.J. Lu wrote:
> On Mon, Apr 8, 2024 at 9:47 AM Adhemerval Zanella Netto
> <adhemerval.zanella@linaro.org> wrote:
>>
>>
>>
>> On 08/04/24 13:06, H.J. Lu wrote:
>>> _dl_signal_error may be called with objname == NULL.  _dl_exception_create
>>> checks objname == NULL.  But fatal_error doesn't.  Check objname before
>>> calling fatal_error.  This fixes BZ #31596.
>>
>> Do we have a reproducer for this? The one from BZ#31596 does seems to trigger
>> it.
> 
> We don't.  But it may happen in theory.

Why not add the test on fatal_error instead? Because if we are adding
possible check for argument where we are not sure that it might trigger,
it is clear to me to add where the issue might happen (besides that our
policy is to avoid adding fixes without proper reproducers).

Also, I think we should close the BZ#31596 as a notabug because the
reproducer does not actually trigger an issue and it is misleading
that this is a glibc issue.

> 
>>> ---
>>>  elf/dl-catch.c | 6 +++++-
>>>  1 file changed, 5 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/elf/dl-catch.c b/elf/dl-catch.c
>>> index 2109516dba..8ef7a4c706 100644
>>> --- a/elf/dl-catch.c
>>> +++ b/elf/dl-catch.c
>>> @@ -126,7 +126,11 @@ _dl_signal_error (int errcode, const char *objname, const char *occasion,
>>>        __longjmp (lcatch->env[0].__jmpbuf, 1);
>>>      }
>>>    else
>>> -    fatal_error (errcode, objname, occasion, errstring);
>>> +    {
>>> +      if (objname == NULL)
>>> +     objname = "";
>>> +      fatal_error (errcode, objname, occasion, errstring);
>>> +    }
>>>  }
>>>  rtld_hidden_def (_dl_signal_error)
>>>