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

[Paul B Mahol]

On 7/8/19, Michael Niedermayer <michael at niedermayer.cc> wrote:
> On Sat, Jun 22, 2019 at 04:58:37PM +0200, Paul B Mahol wrote:
>> 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
>> >
>> > _______________________________________________
>> > ffmpeg-devel mailing list
>> > ffmpeg-devel at ffmpeg.org
>> > https://ffmpeg.org/mailman/listinfo/ffmpeg-devel
>> >
>> > To unsubscribe, visit link above, or email
>> > ffmpeg-devel-request at ffmpeg.org with subject "unsubscribe".
>>
>> In some cases casting in not needed.
>
> unneeded one dropped
>
>
>> Also cant you use sign_extend ?
>
> certainly but that might be slower.
> Do you prefer if i use sign_extend ?

Not if it is slower.

>
> thanks
>
> [...]
> --
> Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
>
> Everything should be made as simple as possible, but not simpler.
> -- Albert Einstein
>