On Fri, May 17, 2013 at 05:35:35PM +0200, Luca Barbato wrote:
> Prevent out of buffer write when decoding broken samples.
> 
> Reported-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
> CC: [email protected]
> ---
>  libavcodec/mjpegdec.c | 5 +++++
>  libavcodec/mjpegdec.h | 7 ++++---
>  2 files changed, 9 insertions(+), 3 deletions(-)
> 
> diff --git a/libavcodec/mjpegdec.c b/libavcodec/mjpegdec.c
> index 896fa99..7a1075d 100644
> --- a/libavcodec/mjpegdec.c
> +++ b/libavcodec/mjpegdec.c
> @@ -941,6 +941,11 @@ static int 
> mjpeg_decode_scan_progressive_ac(MJpegDecodeContext *s, int ss,
>      int16_t *quant_matrix = s->quant_matrixes[s->quant_index[c]];
>      GetBitContext mb_bitmask_gb;
>  
> +    if (ss < 0  || ss >= DCTSIZE2 ||
> +        se < se || se >= DCTSIZE2 ||
           ss somewhere?

> +        Ah < 0  || Al < 0)
> +        return AVERROR_INVALIDDATA;
> +
>      if (mb_bitmask)
>          init_get_bits(&mb_bitmask_gb, mb_bitmask, s->mb_width * 
> s->mb_height);
>  

Introducing DCTSIZE2 is unrelated and constant 64 is bloody obvious to anyone
who knows a thing about JPEG.
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