[FFmpeg-devel] [PATCH] libavcodec/mpegaudiodecheader.c : prevent reserved id misinterpretation

Michael Niedermayer michael at niedermayer.cc
Sun Jul 8 11:58:28 EEST 2018


On Sat, Jul 07, 2018 at 10:29:11PM +0200, Karsten Otto wrote:
> Check the MPEG version ID for the reserved bit pattern 01, and abort header
> parsing in that case. This reduces the chance of misinterpreting arbitrary
> data as a valid frame start, and prevents the resulting audio artifacts.
> ---
>  libavcodec/mpegaudiodecheader.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/libavcodec/mpegaudiodecheader.c b/libavcodec/mpegaudiodecheader.c
> index 6cc79f18b5..23029f186a 100644
> --- a/libavcodec/mpegaudiodecheader.c
> +++ b/libavcodec/mpegaudiodecheader.c
> @@ -46,10 +46,11 @@ int avpriv_mpegaudio_decode_header(MPADecodeHeader *s, uint32_t header)
>      if (header & (1<<20)) {
>          s->lsf = (header & (1<<19)) ? 0 : 1;
>          mpeg25 = 0;
> -    } else {
> +    } else if (!(header & (1<<19))) {
>          s->lsf = 1;
>          mpeg25 = 1;
> -    }
> +    } else
> +        return -1; // reserved id

This check (assuming it breaks no existing mp3) would fit better in
ff_mpa_check_header()

thanks

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

The educated differ from the uneducated as much as the living from the
dead. -- Aristotle 
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 181 bytes
Desc: not available
URL: <http://ffmpeg.org/pipermail/ffmpeg-devel/attachments/20180708/1768af8b/attachment.sig>


More information about the ffmpeg-devel mailing list