| Message ID | 20190514193839.25704-1-michael@niedermayer.cc |
|---|---|
| State | Accepted |
| Commit | c830752142bb5e052d540c429d41fb6dafe920db |
| Headers | show |
On Tue, 14 May 2019 at 20:42, Michael Niedermayer <michael@niedermayer.cc> wrote: > Fixes: Timeout (33sec -> 78ms) > Fixes: > 14668/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_LSCR_fuzzer-5767073352908800 > > Found-by: continuous fuzzing process > https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg > Signed-off-by > <https://github.com/google/oss-fuzz/tree/master/projects/ffmpegSigned-off-by>: > Michael Niedermayer <michael@niedermayer.cc> > --- > libavcodec/pngdec.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/libavcodec/pngdec.c b/libavcodec/pngdec.c > index 6a681be29d..78988d9e75 100644 > --- a/libavcodec/pngdec.c > +++ b/libavcodec/pngdec.c > @@ -1535,6 +1535,9 @@ static int decode_frame_lscr(AVCodecContext *avctx, > AVFrame *frame = data; > int ret, nb_blocks, offset = 0; > > + if (avpkt->size < 2) > + return AVERROR_INVALIDDATA; > + > Why not 1? Or maybe 3? Or maybe 42? Random numbers to fix random samples are just absurd. Kieran
On Tue, May 14, 2019 at 08:52:27PM +0100, Kieran Kunhya wrote: > On Tue, 14 May 2019 at 20:42, Michael Niedermayer <michael@niedermayer.cc> > wrote: > > > Fixes: Timeout (33sec -> 78ms) > > Fixes: > > 14668/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_LSCR_fuzzer-5767073352908800 > > > > Found-by: continuous fuzzing process > > https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg > > Signed-off-by > > <https://github.com/google/oss-fuzz/tree/master/projects/ffmpegSigned-off-by>: > > Michael Niedermayer <michael@niedermayer.cc> > > --- > > libavcodec/pngdec.c | 3 +++ > > 1 file changed, 3 insertions(+) > > > > diff --git a/libavcodec/pngdec.c b/libavcodec/pngdec.c > > index 6a681be29d..78988d9e75 100644 > > --- a/libavcodec/pngdec.c > > +++ b/libavcodec/pngdec.c > > @@ -1535,6 +1535,9 @@ static int decode_frame_lscr(AVCodecContext *avctx, > > AVFrame *frame = data; > > int ret, nb_blocks, offset = 0; > > > > + if (avpkt->size < 2) > > + return AVERROR_INVALIDDATA; > > + > > > > Why not 1? because the code reads 2 bytes next: nb_blocks = bytestream2_get_le16(gb); > Or maybe 3? > Or maybe 42? Its not checking for 3 or 42 or another number because the smallest valid frame that our decoder accepts is 2 bytes. In case you have a specification for LSCR, that would be interresting to read to see if it contains more constraints which would lead to a larger minimum size Thanks > > Random numbers to fix random samples are just absurd. > > Kieran > _______________________________________________ > ffmpeg-devel mailing list > ffmpeg-devel@ffmpeg.org > https://ffmpeg.org/mailman/listinfo/ffmpeg-devel > > To unsubscribe, visit link above, or email > ffmpeg-devel-request@ffmpeg.org with subject "unsubscribe".
On Wed, May 15, 2019 at 05:53:49PM +0200, Michael Niedermayer wrote: > On Tue, May 14, 2019 at 08:52:27PM +0100, Kieran Kunhya wrote: > > On Tue, 14 May 2019 at 20:42, Michael Niedermayer <michael@niedermayer.cc> > > wrote: > > > > > Fixes: Timeout (33sec -> 78ms) > > > Fixes: > > > 14668/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_LSCR_fuzzer-5767073352908800 > > > > > > Found-by: continuous fuzzing process > > > https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg > > > Signed-off-by > > > <https://github.com/google/oss-fuzz/tree/master/projects/ffmpegSigned-off-by>: > > > Michael Niedermayer <michael@niedermayer.cc> > > > --- > > > libavcodec/pngdec.c | 3 +++ > > > 1 file changed, 3 insertions(+) > > > > > > diff --git a/libavcodec/pngdec.c b/libavcodec/pngdec.c > > > index 6a681be29d..78988d9e75 100644 > > > --- a/libavcodec/pngdec.c > > > +++ b/libavcodec/pngdec.c > > > @@ -1535,6 +1535,9 @@ static int decode_frame_lscr(AVCodecContext *avctx, > > > AVFrame *frame = data; > > > int ret, nb_blocks, offset = 0; > > > > > > + if (avpkt->size < 2) > > > + return AVERROR_INVALIDDATA; > > > + > > > > > > > Why not 1? > > because the code reads 2 bytes next: > > nb_blocks = bytestream2_get_le16(gb); > > > > Or maybe 3? > > Or maybe 42? > > Its not checking for 3 or 42 or another number because the smallest > valid frame that our decoder accepts is 2 bytes. > In case you have a specification for LSCR, that would be interresting > to read to see if it contains more constraints which would lead to a > larger minimum size will apply the patch in the next days unless there are objections [...]
diff --git a/libavcodec/pngdec.c b/libavcodec/pngdec.c index 6a681be29d..78988d9e75 100644 --- a/libavcodec/pngdec.c +++ b/libavcodec/pngdec.c @@ -1535,6 +1535,9 @@ static int decode_frame_lscr(AVCodecContext *avctx, AVFrame *frame = data; int ret, nb_blocks, offset = 0; + if (avpkt->size < 2) + return AVERROR_INVALIDDATA; + bytestream2_init(gb, avpkt->data, avpkt->size); if ((ret = ff_get_buffer(avctx, frame, AV_GET_BUFFER_FLAG_REF)) < 0)
Fixes: Timeout (33sec -> 78ms) Fixes: 14668/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_LSCR_fuzzer-5767073352908800 Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg Signed-off-by: Michael Niedermayer <michael@niedermayer.cc> --- libavcodec/pngdec.c | 3 +++ 1 file changed, 3 insertions(+)