| Message ID | 20201212113844.21201-1-michael@niedermayer.cc |
|---|---|
| State | Accepted |
| Commit | 69754e07f5133b20bc789c7dea5d05714f63bf7f |
| Headers | show |
| Series | [FFmpeg-devel,1/2] avformat/wtvdec: Check for EOF before potentially reseting the eof state | expand |
| Context | Check | Description |
|---|---|---|
| andriy/x86_make | success | Make finished |
| andriy/x86_make_fate | success | Make fate finished |
On Sat, Dec 12, 2020 at 12:38:43PM +0100, Michael Niedermayer wrote: > Fixes: infinite loop > Fixes: 28042/clusterfuzz-testcase-minimized-ffmpeg_dem_WTV_fuzzer-6311288967528448 > > Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg > Signed-off-by: Michael Niedermayer <michael@niedermayer.cc> > --- > libavformat/wtvdec.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/libavformat/wtvdec.c b/libavformat/wtvdec.c > index 77908e6392..6c41e3c1a3 100644 > --- a/libavformat/wtvdec.c > +++ b/libavformat/wtvdec.c > @@ -953,6 +953,9 @@ static int parse_chunks(AVFormatContext *s, int mode, int64_t seekts, int *len_p > } else > av_log(s, AV_LOG_WARNING, "unsupported chunk:"FF_PRI_GUID"\n", FF_ARG_GUID(g)); > > + if (avio_feof(pb)) > + break; > + > avio_skip(pb, WTV_PAD8(len) - consumed); > } > return AVERROR_EOF; > -- > 2.17.1 curious how the infinte loop occurs here, as the while loop already tests avio_feof(). i suspect it is because the fuzzed case results in 'consumed > len', and therefore avio_skip is seeking backwards. -- Peter (A907 E02F A6E5 0CD2 34CD 20D2 6760 79C5 AC40 DD6B)
On Sun, Dec 13, 2020 at 07:12:29AM +1100, Peter Ross wrote: > On Sat, Dec 12, 2020 at 12:38:43PM +0100, Michael Niedermayer wrote: > > Fixes: infinite loop > > Fixes: 28042/clusterfuzz-testcase-minimized-ffmpeg_dem_WTV_fuzzer-6311288967528448 > > > > Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg > > Signed-off-by: Michael Niedermayer <michael@niedermayer.cc> > > --- > > libavformat/wtvdec.c | 3 +++ > > 1 file changed, 3 insertions(+) > > > > diff --git a/libavformat/wtvdec.c b/libavformat/wtvdec.c > > index 77908e6392..6c41e3c1a3 100644 > > --- a/libavformat/wtvdec.c > > +++ b/libavformat/wtvdec.c > > @@ -953,6 +953,9 @@ static int parse_chunks(AVFormatContext *s, int mode, int64_t seekts, int *len_p > > } else > > av_log(s, AV_LOG_WARNING, "unsupported chunk:"FF_PRI_GUID"\n", FF_ARG_GUID(g)); > > > > + if (avio_feof(pb)) > > + break; > > + > > avio_skip(pb, WTV_PAD8(len) - consumed); > > } > > return AVERROR_EOF; > > -- > > 2.17.1 > > curious how the infinte loop occurs here, as the while loop already tests avio_feof(). > > i suspect it is because the fuzzed case results in 'consumed > len', and therefore avio_skip is seeking backwards. yes, WTV_PAD8(len) is 88 and consumed is 124 in the testcase, the eof flag is reset from the backward seek and so the other test doesnt trigger thx [...]
diff --git a/libavformat/wtvdec.c b/libavformat/wtvdec.c index 77908e6392..6c41e3c1a3 100644 --- a/libavformat/wtvdec.c +++ b/libavformat/wtvdec.c @@ -953,6 +953,9 @@ static int parse_chunks(AVFormatContext *s, int mode, int64_t seekts, int *len_p } else av_log(s, AV_LOG_WARNING, "unsupported chunk:"FF_PRI_GUID"\n", FF_ARG_GUID(g)); + if (avio_feof(pb)) + break; + avio_skip(pb, WTV_PAD8(len) - consumed); } return AVERROR_EOF;
Fixes: infinite loop Fixes: 28042/clusterfuzz-testcase-minimized-ffmpeg_dem_WTV_fuzzer-6311288967528448 Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg Signed-off-by: Michael Niedermayer <michael@niedermayer.cc> --- libavformat/wtvdec.c | 3 +++ 1 file changed, 3 insertions(+)