[FFmpeg-devel] [PATCH v3] avformat/mp3dec: Fixes misdetection of zYLx.wav

[Hendrik Leppkes]

On Thu, Nov 7, 2019 at 12:38 PM <lance.lmwang at gmail.com> wrote:
>
> From: Limin Wang <lance.lmwang at gmail.com>
>
> Signed-off-by: Limin Wang <lance.lmwang at gmail.com>
> ---
>  libavformat/mp3dec.c | 5 +++++
>  1 file changed, 5 insertions(+)
>
> diff --git a/libavformat/mp3dec.c b/libavformat/mp3dec.c
> index 258f19174b..f15045dd6f 100644
> --- a/libavformat/mp3dec.c
> +++ b/libavformat/mp3dec.c
> @@ -73,6 +73,7 @@ static int mp3_read_probe(const AVProbeData *p)
>      int frames, ret;
>      int framesizes, max_framesizes;
>      uint32_t header;
> +    uint32_t next;
>      const uint8_t *buf, *buf0, *buf2, *end;
>
>      buf0 = p->buf;
> @@ -93,6 +94,10 @@ static int mp3_read_probe(const AVProbeData *p)
>              ret = avpriv_mpegaudio_decode_header(&h, header);
>              if (ret != 0)
>                  break;
> +            next = AV_RB32(buf2 + 4);
> +            /* detect invalid data after header */
> +            if ((header & 0xfffe0000) == (next & 0xfffe0000))
> +                break;
>              buf2 += h.frame_size;
>              framesizes += h.frame_size;
>          }

This seems like one check designed to fix exactly one file. Thats
really not the kind of checks that seem appropriate here.
I'm not sure you can conclusively proof that the data after the header
cannot have a certain bit-pattern, since audio data immediately starts
here.

- Hendrik