diff mbox

[FFmpeg-devel,1/5] avcodec/vp56: Consider the alpha start as end of the prior header

Message ID 20190806213006.25210-1-michael@niedermayer.cc
State Accepted
Commit db78bc1297ebaa51cfe5c80775808ec11ed7512b
Headers show

Commit Message

Michael Niedermayer Aug. 6, 2019, 9:30 p.m. UTC 
Fixes: Timeout (23sec -> 71ms)
Fixes: 15661/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_VP6A_fuzzer-6257865947348992

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
---
 libavcodec/vp56.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

Comments

Peter Ross Aug. 10, 2019, 11:29 p.m. UTC | #1 
On Tue, Aug 06, 2019 at 11:30:02PM +0200, Michael Niedermayer wrote:
> Fixes: Timeout (23sec -> 71ms)
> Fixes: 15661/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_VP6A_fuzzer-6257865947348992
> 
> Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
> Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
> ---
>  libavcodec/vp56.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/libavcodec/vp56.c b/libavcodec/vp56.c
> index 72fea3780e..695f37e972 100644
> --- a/libavcodec/vp56.c
> +++ b/libavcodec/vp56.c
> @@ -572,7 +572,7 @@ int ff_vp56_decode_frame(AVCodecContext *avctx, void *data, int *got_frame,
>      VP56Context *s = avctx->priv_data;
>      AVFrame *const p = s->frames[VP56_FRAME_CURRENT];
>      int remaining_buf_size = avpkt->size;
> -    int av_uninit(alpha_offset);
> +    int alpha_offset = remaining_buf_size;
>      int i, res;
>      int ret;
>  
> @@ -585,7 +585,7 @@ int ff_vp56_decode_frame(AVCodecContext *avctx, void *data, int *got_frame,
>              return AVERROR_INVALIDDATA;
>      }
>  
> -    res = s->parse_header(s, buf, remaining_buf_size);
> +    res = s->parse_header(s, buf, alpha_offset);
>      if (res < 0)
>          return res;
>  

hi michael, i am strugling to see a problem with the existing logic.

    if (s->has_alpha) {
        if (remaining_buf_size < 3)
            return AVERROR_INVALIDDATA;
        alpha_offset = bytestream_get_be24(&buf);
        remaining_buf_size -= 3;
        if (remaining_buf_size < alpha_offset)
            return AVERROR_INVALIDDATA;
    }

    res = s->parse_header(s, buf, remaining_buf_size);
    if (res < 0)
        return res;


if the sample has alpha, remaining_buf_size is reduced in size.
can you post the sanple that takes 23s to decode?

-- Peter
(A907 E02F A6E5 0CD2 34CD 20D2 6760 79C5 AC40 DD6B)
Michael Niedermayer Aug. 11, 2019, 3:02 p.m. UTC | #2 
On Sun, Aug 11, 2019 at 09:29:14AM +1000, Peter Ross wrote:
> On Tue, Aug 06, 2019 at 11:30:02PM +0200, Michael Niedermayer wrote:
> > Fixes: Timeout (23sec -> 71ms)
> > Fixes: 15661/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_VP6A_fuzzer-6257865947348992
> > 
> > Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
> > Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
> > ---
> >  libavcodec/vp56.c | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> > 
> > diff --git a/libavcodec/vp56.c b/libavcodec/vp56.c
> > index 72fea3780e..695f37e972 100644
> > --- a/libavcodec/vp56.c
> > +++ b/libavcodec/vp56.c
> > @@ -572,7 +572,7 @@ int ff_vp56_decode_frame(AVCodecContext *avctx, void *data, int *got_frame,
> >      VP56Context *s = avctx->priv_data;
> >      AVFrame *const p = s->frames[VP56_FRAME_CURRENT];
> >      int remaining_buf_size = avpkt->size;
> > -    int av_uninit(alpha_offset);
> > +    int alpha_offset = remaining_buf_size;
> >      int i, res;
> >      int ret;
> >  
> > @@ -585,7 +585,7 @@ int ff_vp56_decode_frame(AVCodecContext *avctx, void *data, int *got_frame,
> >              return AVERROR_INVALIDDATA;
> >      }
> >  
> > -    res = s->parse_header(s, buf, remaining_buf_size);
> > +    res = s->parse_header(s, buf, alpha_offset);
> >      if (res < 0)
> >          return res;
> >  
> 
> hi michael, i am strugling to see a problem with the existing logic.
> 
>     if (s->has_alpha) {
>         if (remaining_buf_size < 3)
>             return AVERROR_INVALIDDATA;
>         alpha_offset = bytestream_get_be24(&buf);
>         remaining_buf_size -= 3;
>         if (remaining_buf_size < alpha_offset)
>             return AVERROR_INVALIDDATA;
>     }
> 
>     res = s->parse_header(s, buf, remaining_buf_size);
>     if (res < 0)
>         return res;
> 
> 
> if the sample has alpha, remaining_buf_size is reduced in size.

> can you post the sanple that takes 23s to decode?

ill send the sample to you privatly

thanks

[...]
Peter Ross Aug. 12, 2019, 11:03 a.m. UTC | #3 
On Sun, Aug 11, 2019 at 05:02:47PM +0200, Michael Niedermayer wrote:
> On Sun, Aug 11, 2019 at 09:29:14AM +1000, Peter Ross wrote:
> > On Tue, Aug 06, 2019 at 11:30:02PM +0200, Michael Niedermayer wrote:
> > > Fixes: Timeout (23sec -> 71ms)
> > > Fixes: 15661/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_VP6A_fuzzer-6257865947348992
> > > 
> > > Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
> > > Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
> > > ---
> > >  libavcodec/vp56.c | 4 ++--
> > >  1 file changed, 2 insertions(+), 2 deletions(-)
> > > 
> > > diff --git a/libavcodec/vp56.c b/libavcodec/vp56.c
> > > index 72fea3780e..695f37e972 100644
> > > --- a/libavcodec/vp56.c
> > > +++ b/libavcodec/vp56.c
> > > @@ -572,7 +572,7 @@ int ff_vp56_decode_frame(AVCodecContext *avctx, void *data, int *got_frame,
> > >      VP56Context *s = avctx->priv_data;
> > >      AVFrame *const p = s->frames[VP56_FRAME_CURRENT];
> > >      int remaining_buf_size = avpkt->size;
> > > -    int av_uninit(alpha_offset);
> > > +    int alpha_offset = remaining_buf_size;
> > >      int i, res;
> > >      int ret;
> > >  
> > > @@ -585,7 +585,7 @@ int ff_vp56_decode_frame(AVCodecContext *avctx, void *data, int *got_frame,
> > >              return AVERROR_INVALIDDATA;
> > >      }
> > >  
> > > -    res = s->parse_header(s, buf, remaining_buf_size);
> > > +    res = s->parse_header(s, buf, alpha_offset);
> > >      if (res < 0)
> > >          return res;
> > >  
> > 
> > hi michael, i am strugling to see a problem with the existing logic.
> > 
> >     if (s->has_alpha) {
> >         if (remaining_buf_size < 3)
> >             return AVERROR_INVALIDDATA;
> >         alpha_offset = bytestream_get_be24(&buf);
> >         remaining_buf_size -= 3;
> >         if (remaining_buf_size < alpha_offset)
> >             return AVERROR_INVALIDDATA;
> >     }
> > 
> >     res = s->parse_header(s, buf, remaining_buf_size);
> >     if (res < 0)
> >         return res;
> > 
> > 
> > if the sample has alpha, remaining_buf_size is reduced in size.
> 
> > can you post the sanple that takes 23s to decode?
> 
> ill send the sample to you privatly

thanks, was able to reproduce. disregard my comment above regarding remaining_buf_size.

approve.

-- Peter
(A907 E02F A6E5 0CD2 34CD 20D2 6760 79C5 AC40 DD6B)
Michael Niedermayer Aug. 13, 2019, 9:31 a.m. UTC | #4 
On Mon, Aug 12, 2019 at 09:03:41PM +1000, Peter Ross wrote:
> On Sun, Aug 11, 2019 at 05:02:47PM +0200, Michael Niedermayer wrote:
> > On Sun, Aug 11, 2019 at 09:29:14AM +1000, Peter Ross wrote:
> > > On Tue, Aug 06, 2019 at 11:30:02PM +0200, Michael Niedermayer wrote:
> > > > Fixes: Timeout (23sec -> 71ms)
> > > > Fixes: 15661/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_VP6A_fuzzer-6257865947348992
> > > > 
> > > > Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
> > > > Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
> > > > ---
> > > >  libavcodec/vp56.c | 4 ++--
> > > >  1 file changed, 2 insertions(+), 2 deletions(-)
> > > > 
> > > > diff --git a/libavcodec/vp56.c b/libavcodec/vp56.c
> > > > index 72fea3780e..695f37e972 100644
> > > > --- a/libavcodec/vp56.c
> > > > +++ b/libavcodec/vp56.c
> > > > @@ -572,7 +572,7 @@ int ff_vp56_decode_frame(AVCodecContext *avctx, void *data, int *got_frame,
> > > >      VP56Context *s = avctx->priv_data;
> > > >      AVFrame *const p = s->frames[VP56_FRAME_CURRENT];
> > > >      int remaining_buf_size = avpkt->size;
> > > > -    int av_uninit(alpha_offset);
> > > > +    int alpha_offset = remaining_buf_size;
> > > >      int i, res;
> > > >      int ret;
> > > >  
> > > > @@ -585,7 +585,7 @@ int ff_vp56_decode_frame(AVCodecContext *avctx, void *data, int *got_frame,
> > > >              return AVERROR_INVALIDDATA;
> > > >      }
> > > >  
> > > > -    res = s->parse_header(s, buf, remaining_buf_size);
> > > > +    res = s->parse_header(s, buf, alpha_offset);
> > > >      if (res < 0)
> > > >          return res;
> > > >  
> > > 
> > > hi michael, i am strugling to see a problem with the existing logic.
> > > 
> > >     if (s->has_alpha) {
> > >         if (remaining_buf_size < 3)
> > >             return AVERROR_INVALIDDATA;
> > >         alpha_offset = bytestream_get_be24(&buf);
> > >         remaining_buf_size -= 3;
> > >         if (remaining_buf_size < alpha_offset)
> > >             return AVERROR_INVALIDDATA;
> > >     }
> > > 
> > >     res = s->parse_header(s, buf, remaining_buf_size);
> > >     if (res < 0)
> > >         return res;
> > > 
> > > 
> > > if the sample has alpha, remaining_buf_size is reduced in size.
> > 
> > > can you post the sanple that takes 23s to decode?
> > 
> > ill send the sample to you privatly
> 
> thanks, was able to reproduce. disregard my comment above regarding remaining_buf_size.
> 
> approve.

will apply

thx

[...]
diff mbox

Patch

diff --git a/libavcodec/vp56.c b/libavcodec/vp56.c
index 72fea3780e..695f37e972 100644
--- a/libavcodec/vp56.c
+++ b/libavcodec/vp56.c
@@ -572,7 +572,7 @@  int ff_vp56_decode_frame(AVCodecContext *avctx, void *data, int *got_frame,
     VP56Context *s = avctx->priv_data;
     AVFrame *const p = s->frames[VP56_FRAME_CURRENT];
     int remaining_buf_size = avpkt->size;
-    int av_uninit(alpha_offset);
+    int alpha_offset = remaining_buf_size;
     int i, res;
     int ret;
 
@@ -585,7 +585,7 @@  int ff_vp56_decode_frame(AVCodecContext *avctx, void *data, int *got_frame,
             return AVERROR_INVALIDDATA;
     }
 
-    res = s->parse_header(s, buf, remaining_buf_size);
+    res = s->parse_header(s, buf, alpha_offset);
     if (res < 0)
         return res;