Re: [FFmpeg-devel] [PATCH] avcodec/jpeg2000htdec: Check for invalid magref length.

[James Almer <jamrial@gmail.com>]

On 6/5/2023 3:04 PM, etemesicaleb@gmail.com wrote:
> From: caleb <etemesicaleb@gmail.com>
> 
> ---
>   libavcodec/jpeg2000htdec.c | 10 +++++++---
>   1 file changed, 7 insertions(+), 3 deletions(-)
> 
> diff --git a/libavcodec/jpeg2000htdec.c b/libavcodec/jpeg2000htdec.c
> index 51cd96e0f1..474d671ee0 100644
> --- a/libavcodec/jpeg2000htdec.c
> +++ b/libavcodec/jpeg2000htdec.c
> @@ -1101,8 +1101,8 @@ static void jpeg2000_decode_sigprop_segment(Jpeg2000Cblk *cblk, uint16_t width,
>    * See procedure decodeSigPropMag at Rec. ITU-T T.814, 7.5.
>   */
>   static int
> -jpeg2000_decode_magref_segment(Jpeg2000Cblk *cblk, uint16_t width, uint16_t block_height, uint8_t *magref_segment,
> -                       uint32_t magref_length, uint8_t pLSB, int32_t *sample_buf, uint8_t *block_states)
> +jpeg2000_decode_magref_segment(const Jpeg2000DecoderContext *s,Jpeg2000Cblk *cblk, uint16_t width, uint16_t block_height, uint8_t *magref_segment,
> +                               uint32_t magref_length, uint8_t pLSB, int32_t *sample_buf, uint8_t *block_states)

This could be split in three lines.

>   {
>   
>       StateVars mag_ref           = { 0 };
> @@ -1111,6 +1111,10 @@ jpeg2000_decode_magref_segment(Jpeg2000Cblk *cblk, uint16_t width, uint16_t bloc
>       uint16_t i_start            = 0;
>       int32_t *sp;
>   
> +    if (magref_length < 2){
> +        av_log(s->avctx,AV_LOG_ERROR,"Invalid magnitude refinement length\n");
> +        return AVERROR_INVALIDDATA;
> +    }

Why not add this check and log call before calling 
jpeg2000_decode_magref_segment()? That way you don't need to add 
Jpeg2000DecoderContext as a parameter to it.

>       jpeg2000_init_mag_ref(&mag_ref, magref_length);
>   
>       for (int n1 = 0; n1 < num_v_stripe; n1++) {
> @@ -1261,7 +1265,7 @@ ff_jpeg2000_decode_htj2k(const Jpeg2000DecoderContext *s, Jpeg2000CodingStyle *c
>                                   pLSB - 1, sample_buf, block_states);
>   
>       if (cblk->npasses > 2)
> -        if ((ret = jpeg2000_decode_magref_segment(cblk, width, height, Dref, Lref,
> +        if ((ret = jpeg2000_decode_magref_segment(s,cblk, width, height, Dref, Lref,
>                                             pLSB - 1, sample_buf, block_states)) < 0)
>               goto free;
>   
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