[FFmpeg-devel] [PATCH] avcodec/vvc_mp4toannexb: check the return of bytestream2_get_buffer

[FFmpeg-devel] [PATCH] avcodec/vvc_mp4toannexb: check the return of bytestream2_get_buffer

[Nuo Mi]

Fixes: fuzzer timeout
Fixes: 65253/clusterfuzz-testcase-minimized-ffmpeg_BSF_VVC_MP4TOANNEXB_fuzzer-4972412487467008

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
---
 libavcodec/bsf/vvc_mp4toannexb.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/libavcodec/bsf/vvc_mp4toannexb.c b/libavcodec/bsf/vvc_mp4toannexb.c
index 25c3726918..a15c1eef5b 100644
--- a/libavcodec/bsf/vvc_mp4toannexb.c
+++ b/libavcodec/bsf/vvc_mp4toannexb.c
@@ -168,8 +168,10 @@ static int vvc_extradata_to_annexb(AVBSFContext *ctx)
                 goto fail;
 
             AV_WB32(new_extradata + new_extradata_size, 1); // add the startcode
-            bytestream2_get_buffer(&gb, new_extradata + new_extradata_size + 4,
-                                   nalu_len);
+            if (bytestream2_get_buffer(&gb, new_extradata + new_extradata_size + 4, nalu_len) != nalu_len) {
+                ret = AVERROR_INVALIDDATA;
+                goto fail;
+            }
             new_extradata_size += 4 + nalu_len;
             memset(new_extradata + new_extradata_size, 0,
                    AV_INPUT_BUFFER_PADDING_SIZE);
@@ -298,8 +300,10 @@ static int vvc_mp4toannexb_filter(AVBSFContext *ctx, AVPacket *out)
         if (extra_size)
             memcpy(out->data + prev_size, ctx->par_out->extradata, extra_size);
         AV_WB32(out->data + prev_size + extra_size, 1);
-        bytestream2_get_buffer(&gb, out->data + prev_size + 4 + extra_size,
-                               nalu_size);
+        if (bytestream2_get_buffer(&gb, out->data + prev_size + 4 + extra_size, nalu_size) != nalu_size) {
+            ret = AVERROR_INVALIDDATA;
+            goto fail;
+        }
     }
 
     ret = av_packet_copy_props(out, in);
-- 
2.25.1

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Re: [FFmpeg-devel] [PATCH] avcodec/vvc_mp4toannexb: check the return of bytestream2_get_buffer

[Andreas Rheinhardt]

Nuo Mi:
> Fixes: fuzzer timeout
> Fixes: 65253/clusterfuzz-testcase-minimized-ffmpeg_BSF_VVC_MP4TOANNEXB_fuzzer-4972412487467008
> 
> Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
> Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
> ---
>  libavcodec/bsf/vvc_mp4toannexb.c | 12 ++++++++----
>  1 file changed, 8 insertions(+), 4 deletions(-)
> 
> diff --git a/libavcodec/bsf/vvc_mp4toannexb.c b/libavcodec/bsf/vvc_mp4toannexb.c
> index 25c3726918..a15c1eef5b 100644
> --- a/libavcodec/bsf/vvc_mp4toannexb.c
> +++ b/libavcodec/bsf/vvc_mp4toannexb.c
> @@ -168,8 +168,10 @@ static int vvc_extradata_to_annexb(AVBSFContext *ctx)
>                  goto fail;
>  
>              AV_WB32(new_extradata + new_extradata_size, 1); // add the startcode
> -            bytestream2_get_buffer(&gb, new_extradata + new_extradata_size + 4,
> -                                   nalu_len);
> +            if (bytestream2_get_buffer(&gb, new_extradata + new_extradata_size + 4, nalu_len) != nalu_len) {
> +                ret = AVERROR_INVALIDDATA;
> +                goto fail;
> +            }
>              new_extradata_size += 4 + nalu_len;
>              memset(new_extradata + new_extradata_size, 0,
>                     AV_INPUT_BUFFER_PADDING_SIZE);
> @@ -298,8 +300,10 @@ static int vvc_mp4toannexb_filter(AVBSFContext *ctx, AVPacket *out)
>          if (extra_size)
>              memcpy(out->data + prev_size, ctx->par_out->extradata, extra_size);
>          AV_WB32(out->data + prev_size + extra_size, 1);
> -        bytestream2_get_buffer(&gb, out->data + prev_size + 4 + extra_size,
> -                               nalu_size);
> +        if (bytestream2_get_buffer(&gb, out->data + prev_size + 4 + extra_size, nalu_size) != nalu_size) {
> +            ret = AVERROR_INVALIDDATA;
> +            goto fail;
> +        }
>      }
>  
>      ret = av_packet_copy_props(out, in);

It is better to check that there is enough input before growing the
packet/the extradata. This also allows to use unchecked reads lateron.

- Andreas

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Re: [FFmpeg-devel] [PATCH] avcodec/vvc_mp4toannexb: check the return of bytestream2_get_buffer

[Nuo Mi]

On Thu, Feb 8, 2024 at 11:50 PM Andreas Rheinhardt <
andreas.rheinhardt@outlook.com> wrote:

> Nuo Mi:
> > Fixes: fuzzer timeout
> > Fixes:
> 65253/clusterfuzz-testcase-minimized-ffmpeg_BSF_VVC_MP4TOANNEXB_fuzzer-4972412487467008
> >
> > Found-by: continuous fuzzing process
> https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
> > Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
> > ---
> >  libavcodec/bsf/vvc_mp4toannexb.c | 12 ++++++++----
> >  1 file changed, 8 insertions(+), 4 deletions(-)
> >
> > diff --git a/libavcodec/bsf/vvc_mp4toannexb.c
> b/libavcodec/bsf/vvc_mp4toannexb.c
> > index 25c3726918..a15c1eef5b 100644
> > --- a/libavcodec/bsf/vvc_mp4toannexb.c
> > +++ b/libavcodec/bsf/vvc_mp4toannexb.c
> > @@ -168,8 +168,10 @@ static int vvc_extradata_to_annexb(AVBSFContext
> *ctx)
> >                  goto fail;
> >
> >              AV_WB32(new_extradata + new_extradata_size, 1); // add the
> startcode
> > -            bytestream2_get_buffer(&gb, new_extradata +
> new_extradata_size + 4,
> > -                                   nalu_len);
> > +            if (bytestream2_get_buffer(&gb, new_extradata +
> new_extradata_size + 4, nalu_len) != nalu_len) {
> > +                ret = AVERROR_INVALIDDATA;
> > +                goto fail;
> > +            }
> >              new_extradata_size += 4 + nalu_len;
> >              memset(new_extradata + new_extradata_size, 0,
> >                     AV_INPUT_BUFFER_PADDING_SIZE);
> > @@ -298,8 +300,10 @@ static int vvc_mp4toannexb_filter(AVBSFContext
> *ctx, AVPacket *out)
> >          if (extra_size)
> >              memcpy(out->data + prev_size, ctx->par_out->extradata,
> extra_size);
> >          AV_WB32(out->data + prev_size + extra_size, 1);
> > -        bytestream2_get_buffer(&gb, out->data + prev_size + 4 +
> extra_size,
> > -                               nalu_size);
> > +        if (bytestream2_get_buffer(&gb, out->data + prev_size + 4 +
> extra_size, nalu_size) != nalu_size) {
> > +            ret = AVERROR_INVALIDDATA;
> > +            goto fail;
> > +        }
> >      }
> >
> >      ret = av_packet_copy_props(out, in);
>
> It is better to check that there is enough input before growing the
> packet/the extradata. This also allows to use unchecked reads lateron.
>
Good idea, fixed in v2.

>
> - 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-request@ffmpeg.org with subject "unsubscribe".
>
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