Re: [FFmpeg-devel] [PATCH 4/4] avformat/iamf: Check language_label

[James Almer <jamrial@gmail.com>]

On 3/20/2024 10:15 PM, Michael Niedermayer wrote:
> Fixes: null pointer dereference
> Fixes: 67023/clusterfuzz-testcase-minimized-ffmpeg_dem_IAMF_fuzzer-6011025237278720
> 
> Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
> Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
> ---
>   libavformat/iamf.c | 7 ++++---
>   1 file changed, 4 insertions(+), 3 deletions(-)
> 
> diff --git a/libavformat/iamf.c b/libavformat/iamf.c
> index 5de70dc082..f2c22ce3aa 100644
> --- a/libavformat/iamf.c
> +++ b/libavformat/iamf.c
> @@ -89,9 +89,10 @@ void ff_iamf_free_mix_presentation(IAMFMixPresentation **pmix_presentation)
>       if (!mix_presentation)
>           return;
>   
> -    for (int i = 0; i < mix_presentation->count_label; i++)
> -        av_free(mix_presentation->language_label[i]);
> -    av_free(mix_presentation->language_label);
> +    if (mix_presentation->language_label)

If count_label is not 0, then language_label should be allocated.

> +        for (int i = 0; i < mix_presentation->count_label; i++)
> +            av_free(mix_presentation->language_label[i]);
> +    av_freep(&mix_presentation->language_label);
>       av_iamf_mix_presentation_free(&mix_presentation->mix);
>       av_freep(pmix_presentation);
>   }

Can you test the following?

> diff --git a/libavformat/iamf_parse.c b/libavformat/iamf_parse.c
> index cb49cf0a57..e29c2c6b6c 100644
> --- a/libavformat/iamf_parse.c
> +++ b/libavformat/iamf_parse.c
> @@ -822,6 +822,7 @@ static int mix_presentation_obu(void *s, IAMFContext *c, AVIOContext *pb, int le
>      mix_presentation->language_label = av_calloc(mix_presentation->count_label,
>                                                   sizeof(*mix_presentation->language_label));
>      if (!mix_presentation->language_label) {
> +        mix_presentation->count_label = 0;
>          ret = AVERROR(ENOMEM);
>          goto fail;
>      }

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