On Fri, Jul 30, 2021 at 12:16 AM Andreas Rheinhardt < andreas.rheinha...@outlook.com> wrote:
> Andreas Rheinhardt: > > Michael Niedermayer: > >> Fixes: reading over the end > >> Fixes: > 36346/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_ARGO_fuzzer-5366943107383296 > >> > >> Found-by: continuous fuzzing process > https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg > >> Signed-off-by: Michael Niedermayer <mich...@niedermayer.cc> > >> --- > >> libavcodec/argo.c | 2 ++ > >> 1 file changed, 2 insertions(+) > >> > >> diff --git a/libavcodec/argo.c b/libavcodec/argo.c > >> index bbdb6ae15f..79a44d2583 100644 > >> --- a/libavcodec/argo.c > >> +++ b/libavcodec/argo.c > >> @@ -116,6 +116,8 @@ static int decode_alcd(AVCodecContext *avctx, > AVFrame *frame) > >> int index; > >> > >> if (count == 0) { > >> + if (bytestream2_get_bytes_left(gb) < 1) > >> + return AVERROR_INVALIDDATA; > >> codes = bytestream2_get_byteu(&sb); > >> count = 8; > >> } > >> > > Does the following also fix the issue? > > > > diff --git a/libavcodec/argo.c b/libavcodec/argo.c > > > > index bbdb6ae15f..602c042568 100644 > > > > --- a/libavcodec/argo.c > > > > +++ b/libavcodec/argo.c > > > > @@ -102,13 +102,14 @@ static int decode_alcd(AVCodecContext *avctx, > > AVFrame *frame) > > > > uint8_t *dst = frame->data[0]; > > > > uint8_t codes = 0; > > > > int count = 0; > > > > + int num_codes = ((frame->width + 1) / 2 * (frame->height + 1) / 2 + > > 7) >> 3; > > > > > > > > - if (bytestream2_get_bytes_left(gb) < 1024 + (((frame->width / 2) * > > (frame->height / 2) + 7) >> 3)) > > > > + if (bytestream2_get_bytes_left(gb) < 1024 + num_codes) > > > > return AVERROR_INVALIDDATA; > > > > > > > > bytestream2_skipu(gb, 1024); > > > > sb = *gb; > > > > - bytestream2_skipu(gb, ((frame->width / 2) * (frame->height / 2) + > > 7) >> 3); > > > > + bytestream2_skipu(gb, num_codes); > > > > > > > > for (int y = 0; y < frame->height; y += 2) { > > > > for (int x = 0; x < frame->width; x += 2) { > > > As can be seen from the above patch, my guess is that odd dimensions are > the cause (because num_codes as above is the number of codes that is > actually read); but my patch would not only change the criterion for > when to error out, but also how much to skip (i.e. where the real data > begins) and this makes me wonder whether we should not error out in this > case (and ask for a sample). > I like Andreas solution much more, anway original video files are having even dimensions, so there is nothing to worry. > - Andreas > _______________________________________________ > ffmpeg-devel mailing list > ffmpeg-devel@ffmpeg.org > https://ffmpeg.org/mailman/listinfo/ffmpeg-devel > > To unsubscribe, visit link above, or email > ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe". > _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe".
