[FFmpeg-devel] [PATCH 6/6] avformat/concatdec: use av_strstart()

[Andreas Rheinhardt]

Michael Niedermayer:
> Fixes: out array read
> Fixes: 26610/clusterfuzz-testcase-minimized-ffmpeg_dem_CONCAT_fuzzer-5631838049271808
> 
> 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/concatdec.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/libavformat/concatdec.c b/libavformat/concatdec.c
> index 4b56b61404..6d5b9914f9 100644
> --- a/libavformat/concatdec.c
> +++ b/libavformat/concatdec.c
> @@ -113,7 +113,8 @@ static int add_file(AVFormatContext *avf, char *filename, ConcatFile **rfile,
>      ConcatFile *file;
>      char *url = NULL;
>      const char *proto;
> -    size_t url_len, proto_len;
> +    const char *ptr;
> +    size_t url_len;
>      int ret;
>  
>      if (cat->safe > 0 && !safe_filename(filename)) {
> @@ -122,9 +123,8 @@ static int add_file(AVFormatContext *avf, char *filename, ConcatFile **rfile,
>      }
>  
>      proto = avio_find_protocol_name(filename);
> -    proto_len = proto ? strlen(proto) : 0;
> -    if (proto && !memcmp(filename, proto, proto_len) &&
> -        (filename[proto_len] == ':' || filename[proto_len] == ',')) {
> +    if (proto && av_strstart(filename, proto, &ptr) &&
> +        (*ptr == ':' || *ptr == ',')) {
>          url = filename;
>          filename = NULL;
>      } else {
> 
LGTM.

- Andreas