[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
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