Re: "Perfect" MP3 fails to import

With that mp3 file we reach this point in layer3.c, with cachesz == 20 and
bits_left == -22

  if (cachesz + bits_left < 0)
    return MAD_ERROR_BADHUFFDATA;  /* big_values overrun */


There's a patch here that addresses length issues and changes that code:
https://fossies.org/linux/avidemux/avidemux_plugins/ADM_audioDecoders/ADM_ad_mad/patches/length-check.patch

   635 +     if (cachesz - fakebits < 1)  636 +       return
MAD_ERROR_BADHUFFDATA;  637       xrptr[1] = MASK1BIT(bitcache,
cachesz--) ?  638         -requantized : requantized;  639     }  640
@@ -1155,9 +1221,6 @@ enum mad_error III_huffdecode(struct mad  641
  }  642    }  643    644 -  if (cachesz + bits_left < 0)  645 -
return MAD_ERROR_BADHUFFDATA;  /* big_values overrun */  646 -  647


The patch looks pretty extensive.

    From: Kurt Roeckx <[email protected]>
    Date: Sun, 28 Jan 2018 19:26:36 +0100
    Subject: Check the size before reading with mad_bit_read

    There are various cases where it attempts to read past the end of the
buffer
    using mad_bit_read(). Most functions didn't even know the size of the
buffer
    they were reading from.

We are using libmad 0.15.1b.
Debian have  0.15.2b-9 with these fixes from 2018 in.

This would need careful review.  Probably worth contacting Kurt Roeckx too,
to confirm we're understanding things correctly, and say thank you.

--James.




On Thu, 15 Apr 2021 at 15:48, Steve Fiddle <[email protected]> wrote:

>
>
> On Thu, 15 Apr 2021 at 15:41, James Crook <[email protected]> wrote:
>
>> Your first message never made it to this list (I just checked the
>> archive).
>> What's the link for the mp3?
>>
>
> You can get it here:
> https://drive.google.com/file/d/1qCPXtsBfFII2NwsSVMZY9k-Lx6sbhlS8/view?usp=sharing
>
> Steve
>
>
>>
>> On Thu, 15 Apr 2021 at 15:35, Steve Fiddle <[email protected]>
>> wrote:
>>
>>> Good detective work James.
>>>
>>> Any ideas about the MP3 file (first post of this thread)? Given your
>>> explanation of the OGG problem, I assume that it is a different issue.
>>>
>>> I'm thinking that it is probably an Audacity bug because the file
>>> appears to be a valid MP3 file. On the other hand, if the MP3 is malformed
>>> (in some way that I've not been able to detect), then it's rather more open
>>> to opinion whether or not it is an Audacity bug, or a bug in the
>>> application that created it.
>>>
>>> Steve
>>>
>>> On Thu, 15 Apr 2021 at 13:43, James Crook <[email protected]>
>>> wrote:
>>>
>>>> Logged as: https://bugzilla.audacityteam.org/show_bug.cgi?id=2748
>>>>
>>>>
>>>> On Thu, 15 Apr 2021 at 13:27, James Crook <[email protected]>
>>>> wrote:
>>>>
>>>>> It's the same infinite loop as JUCE had:
>>>>>
>>>>>
>>>>> https://forum.juce.com/t/ogg-vorbis-file-puts-juce-oggreader-in-infinite-loop/41148
>>>>>
>>>>> So will be fixed if we upgrade to 1.3.7 or later.
>>>>>
>>>>> On Thu, 15 Apr 2021 at 13:00, James Crook <[email protected]>
>>>>> wrote:
>>>>>
>>>>>> On both 3.0.2 and 2.4.2 it's stuck in library file, vorbisfile.c
>>>>>>
>>>>>> static int _fseek64_wrap(FILE *f,ogg_int64_t off,int whence){
>>>>>>   if(f==NULL)return(-1);
>>>>>>   return fseek(f,off,whence);
>>>>>> }
>>>>>>
>>>>>> 'off' and 'whence' are both zero ( SEEK_SET ==0, SEEK_CUR==1,
>>>>>> SEEK_END==2).  We're compiled 32 bit on windows.  Anyone know if it hangs
>>>>>> on mac/linux (compiled 64 bit) too?
>>>>>>
>>>>>> --James.
>>>>>>
>>>>>>
>>>>>> On Thu, 15 Apr 2021 at 12:31, James Crook <[email protected]>
>>>>>> wrote:
>>>>>>
>>>>>>> Confirmed freezes for me on Windows.
>>>>>>>
>>>>>>> On Thu, 15 Apr 2021 at 12:20, Steve Fiddle <[email protected]>
>>>>>>> wrote:
>>>>>>>
>>>>>>>> And by "coincidence" (?), a problem reported importing this ogg
>>>>>>>> file:
>>>>>>>>
>>>>>>>> https://upload.wikimedia.org/wikipedia/commons/0/0f/Claude_Debussy_-_Premi%C3%A8re_Arabesque_-_Patrizia_Prati.ogg
>>>>>>>>
>>>>>>>> As with the MP3 file, it can be imported if you select the
>>>>>>>> "FFmpeg-compatible files" filter, but in this case, using Audacity's native
>>>>>>>> OGG importer causes Audacity to freeze on both Windows and Linux (not
>>>>>>>> tested on macOS).
>>>>>>>>
>>>>>>>> I don't like coincidences as they may be indicating a deeper
>>>>>>>> problem.
>>>>>>>>
>>>>>>>> Steve
>>>>>>>>
>>>>>>>> On Thu, 15 Apr 2021 at 12:01, Steve Fiddle <
>>>>>>>> [email protected]> wrote:
>>>>>>>>
>>>>>>>>> I've tested the attached file with multiple tools in Linux and it
>>>>>>>>> appears to be perfectly formed, yet Audacity still complains that it is
>>>>>>>>> malformed and refuses to import it.
>>>>>>>>>
>>>>>>>>> Steve
>>>>>>>>>
>>>>>>>> _______________________________________________
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