Re: [FFmpeg-devel] [PATCH 2/2] avcodec/pngdec: Check nb_blocks

2019-05-24 Thread Paul B Mahol 
On 5/24/19, Michael Niedermayer  wrote:
> On Sun, Apr 28, 2019 at 12:37:12PM +0200, Paul B Mahol wrote:
>> On 4/28/19, Michael Niedermayer  wrote:
>> > Fixes: Timeout (23sec -> 0.5sec)
>> > Fixes:
>> > 14329/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_LSCR_fuzzer-5679252923482112
>> >
>> > Found-by: continuous fuzzing process
>> > https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
>> > Signed-off-by: Michael Niedermayer 
>> > ---
>> >  libavcodec/pngdec.c | 2 ++
>> >  1 file changed, 2 insertions(+)
>> >
>> > diff --git a/libavcodec/pngdec.c b/libavcodec/pngdec.c
>> > index 6a681be29d..1dcde6cbc9 100644
>> > --- a/libavcodec/pngdec.c
>> > +++ b/libavcodec/pngdec.c
>> > @@ -1541,6 +1541,8 @@ static int decode_frame_lscr(AVCodecContext
>> > *avctx,
>> >  return ret;
>> >
>> >  nb_blocks = bytestream2_get_le16(gb);
>> > +if (2 + nb_blocks * 12 > bytestream2_get_bytes_left(gb))
>>
>> I prefer if this is not reversed.
>
> of course, will unreverse and push as "if (bytestream2_get_bytes_left(gb) <
> 2 + nb_blocks * 12)"
>
> thanks


OK.
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Re: [FFmpeg-devel] [PATCH 2/2] avcodec/pngdec: Check nb_blocks

2019-05-24 Thread Michael Niedermayer 
On Sun, Apr 28, 2019 at 12:37:12PM +0200, Paul B Mahol wrote:
> On 4/28/19, Michael Niedermayer  wrote:
> > Fixes: Timeout (23sec -> 0.5sec)
> > Fixes:
> > 14329/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_LSCR_fuzzer-5679252923482112
> >
> > Found-by: continuous fuzzing process
> > https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
> > Signed-off-by: Michael Niedermayer 
> > ---
> >  libavcodec/pngdec.c | 2 ++
> >  1 file changed, 2 insertions(+)
> >
> > diff --git a/libavcodec/pngdec.c b/libavcodec/pngdec.c
> > index 6a681be29d..1dcde6cbc9 100644
> > --- a/libavcodec/pngdec.c
> > +++ b/libavcodec/pngdec.c
> > @@ -1541,6 +1541,8 @@ static int decode_frame_lscr(AVCodecContext *avctx,
> >  return ret;
> >
> >  nb_blocks = bytestream2_get_le16(gb);
> > +if (2 + nb_blocks * 12 > bytestream2_get_bytes_left(gb))
> 
> I prefer if this is not reversed.

of course, will unreverse and push as "if (bytestream2_get_bytes_left(gb) < 2 + 
nb_blocks * 12)"

thanks

[...]
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Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

There will always be a question for which you do not know the correct answer.


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Re: [FFmpeg-devel] [PATCH 2/2] avcodec/pngdec: Check nb_blocks

2019-04-28 Thread Paul B Mahol 
On 4/28/19, Michael Niedermayer  wrote:
> Fixes: Timeout (23sec -> 0.5sec)
> Fixes:
> 14329/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_LSCR_fuzzer-5679252923482112
>
> Found-by: continuous fuzzing process
> https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
> Signed-off-by: Michael Niedermayer 
> ---
>  libavcodec/pngdec.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/libavcodec/pngdec.c b/libavcodec/pngdec.c
> index 6a681be29d..1dcde6cbc9 100644
> --- a/libavcodec/pngdec.c
> +++ b/libavcodec/pngdec.c
> @@ -1541,6 +1541,8 @@ static int decode_frame_lscr(AVCodecContext *avctx,
>  return ret;
>
>  nb_blocks = bytestream2_get_le16(gb);
> +if (2 + nb_blocks * 12 > bytestream2_get_bytes_left(gb))

I prefer if this is not reversed.

> +return AVERROR_INVALIDDATA;
>
>  if (s->last_picture.f->data[0]) {
>  ret = av_frame_copy(frame, s->last_picture.f);
> --
> 2.21.0
>
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[FFmpeg-devel] [PATCH 2/2] avcodec/pngdec: Check nb_blocks

2019-04-28 Thread Michael Niedermayer 
Fixes: Timeout (23sec -> 0.5sec)
Fixes: 
14329/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_LSCR_fuzzer-5679252923482112

Found-by: continuous fuzzing process 
https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer 
---
 libavcodec/pngdec.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/libavcodec/pngdec.c b/libavcodec/pngdec.c
index 6a681be29d..1dcde6cbc9 100644
--- a/libavcodec/pngdec.c
+++ b/libavcodec/pngdec.c
@@ -1541,6 +1541,8 @@ static int decode_frame_lscr(AVCodecContext *avctx,
 return ret;
 
 nb_blocks = bytestream2_get_le16(gb);
+if (2 + nb_blocks * 12 > bytestream2_get_bytes_left(gb))
+return AVERROR_INVALIDDATA;
 
 if (s->last_picture.f->data[0]) {
 ret = av_frame_copy(frame, s->last_picture.f);
-- 
2.21.0

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