[FFmpeg-devel] [PATCH 1/4] avcodec/prosumer: Check for bytestream eof in decompress()

[Hendrik Leppkes]

On Wed, Oct 31, 2018 at 12:03 PM Michael Niedermayer
<michael at niedermayer.cc> wrote:
>
> Fixes: Infinite loop
> Fixes: 10685/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_PROSUMER_fuzzer-5652236881887232
>
> Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
> Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
> ---
>  libavcodec/prosumer.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/libavcodec/prosumer.c b/libavcodec/prosumer.c
> index 6e98677b55..2fd9880ee1 100644
> --- a/libavcodec/prosumer.c
> +++ b/libavcodec/prosumer.c
> @@ -57,7 +57,7 @@ static int decompress(GetByteContext *gb, int size, PutByteContext *pb, const ui
>      b = lut[2 * idx];
>
>      while (1) {
> -        if (bytestream2_get_bytes_left_p(pb) <= 0)
> +        if (bytestream2_get_bytes_left_p(pb) <= 0 || bytestream2_get_eof(pb))
>              return 0;
>          if (((b & 0xFF00u) != 0x8000u) || (b & 0xFFu)) {
>              if ((b & 0xFF00u) != 0x8000u) {

Why does bytestream2_get_bytes_left_p not return <= 0 at eof, where
there certainly arent any bytes left?

- Hendrik