[FFmpeg-devel] [PATCH 4/6] avcodec/flicvideo: Make line_packets int

[Paul B Mahol]

On 6/22/19, Michael Niedermayer <michael at niedermayer.cc> wrote:
> Fixes: signed integer overflow: -32768 * 196032 cannot be represented in
> type 'int'
> Fixes:
> 15300/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_FLIC_fuzzer-5733319519502336
>
> 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/flicvideo.c | 14 +++++++-------
>  1 file changed, 7 insertions(+), 7 deletions(-)
>
> diff --git a/libavcodec/flicvideo.c b/libavcodec/flicvideo.c
> index ba5bda48c4..cd9cd089af 100644
> --- a/libavcodec/flicvideo.c
> +++ b/libavcodec/flicvideo.c
> @@ -175,7 +175,7 @@ static int flic_decode_frame_8BPP(AVCodecContext *avctx,
>      int lines;
>      int compressed_lines;
>      int starting_line;
> -    signed short line_packets;
> +    int line_packets;
>      int y_ptr;
>      int byte_run;
>      int pixel_skip;
> @@ -274,7 +274,7 @@ static int flic_decode_frame_8BPP(AVCodecContext *avctx,
>                      break;
>                  if (y_ptr > pixel_limit)
>                      return AVERROR_INVALIDDATA;
> -                line_packets = bytestream2_get_le16(&g2);
> +                line_packets = (int16_t)bytestream2_get_le16(&g2);
>                  if ((line_packets & 0xC000) == 0xC000) {
>                      // line skip opcode
>                      line_packets = -line_packets;
> @@ -340,7 +340,7 @@ static int flic_decode_frame_8BPP(AVCodecContext *avctx,
>                  pixel_countdown = s->avctx->width;
>                  if (bytestream2_tell(&g2) + 1 > stream_ptr_after_chunk)
>                      break;
> -                line_packets = bytestream2_get_byte(&g2);
> +                line_packets = (int16_t)bytestream2_get_byte(&g2);
>                  if (line_packets > 0) {
>                      for (i = 0; i < line_packets; i++) {
>                          /* account for the skip bytes */
> @@ -508,7 +508,7 @@ static int flic_decode_frame_15_16BPP(AVCodecContext
> *avctx,
>
>      int lines;
>      int compressed_lines;
> -    signed short line_packets;
> +    int line_packets;
>      int y_ptr;
>      int byte_run;
>      int pixel_skip;
> @@ -572,7 +572,7 @@ static int flic_decode_frame_15_16BPP(AVCodecContext
> *avctx,
>                      break;
>                  if (y_ptr > pixel_limit)
>                      return AVERROR_INVALIDDATA;
> -                line_packets = bytestream2_get_le16(&g2);
> +                line_packets = (int16_t)bytestream2_get_le16(&g2);
>                  if (line_packets < 0) {
>                      line_packets = -line_packets;
>                      if (line_packets > s->avctx->height)
> @@ -806,7 +806,7 @@ static int flic_decode_frame_24BPP(AVCodecContext
> *avctx,
>
>      int lines;
>      int compressed_lines;
> -    signed short line_packets;
> +    int line_packets;
>      int y_ptr;
>      int byte_run;
>      int pixel_skip;
> @@ -870,7 +870,7 @@ static int flic_decode_frame_24BPP(AVCodecContext
> *avctx,
>                      break;
>                  if (y_ptr > pixel_limit)
>                      return AVERROR_INVALIDDATA;
> -                line_packets = bytestream2_get_le16(&g2);
> +                line_packets = (int16_t)bytestream2_get_le16(&g2);
>                  if (line_packets < 0) {
>                      line_packets = -line_packets;
>                      if (line_packets > s->avctx->height)
> --
> 2.22.0
>
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In some cases casting in not needed.
Also cant you use sign_extend ?