[FFmpeg-devel] [PATCH] avformat/utils: check for integer overflow in av_get_frame_filename2()

[Paul B Mahol]

On 8/16/20, Michael Niedermayer <michael at niedermayer.cc> wrote:
> Fixes: signed integer overflow: 317316873 * 10 cannot be represented in type
> 'int'
> Fixes:
> 24708/clusterfuzz-testcase-minimized-ffmpeg_DEMUXER_fuzzer-5731180885049344
>
> Found-by: continuous fuzzing process
> https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
> Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
> ---
>  libavformat/utils.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/libavformat/utils.c b/libavformat/utils.c
> index 807d9f10cb..60e6fe5be5 100644
> --- a/libavformat/utils.c
> +++ b/libavformat/utils.c
> @@ -4745,8 +4745,11 @@ int av_get_frame_filename2(char *buf, int buf_size,
> const char *path, int number
>          if (c == '%') {
>              do {
>                  nd = 0;
> -                while (av_isdigit(*p))
> +                while (av_isdigit(*p)) {
> +                    if (nd >= INT_MAX / 10 - 255)
> +                        goto fail;
>                      nd = nd * 10 + *p++ - '0';
> +                }
>                  c = *p++;
>              } while (av_isdigit(c));
>

Why to limit it?
Use int64_t?

> --
> 2.17.1
>
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