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[FFmpeg-devel,3/3] avformat/rmdec: Check codec_length without overflow

Message ID 20210215202313.1228-3-michael@niedermayer.cc
State Accepted
Headers show
Series [FFmpeg-devel,1/3] avcodec/vp8: Move end check into MB loop in vp78_decode_mv_mb_modes() | expand

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Commit Message

Michael Niedermayer Feb. 15, 2021, 8:23 p.m. UTC 
Fixes: signed integer overflow: 2147483647 + 64 cannot be represented in type 'int'
Fixes: 30333/clusterfuzz-testcase-minimized-ffmpeg_dem_RM_fuzzer-5175286983426048

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

Comments

Andreas Rheinhardt Feb. 15, 2021, 8:38 p.m. UTC | #1 
Michael Niedermayer:
> Fixes: signed integer overflow: 2147483647 + 64 cannot be represented in type 'int'
> Fixes: 30333/clusterfuzz-testcase-minimized-ffmpeg_dem_RM_fuzzer-5175286983426048
> 
> Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
> Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
> ---
>  libavformat/rmdec.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/libavformat/rmdec.c b/libavformat/rmdec.c
> index 521b9d0e8c..613fb407df 100644
> --- a/libavformat/rmdec.c
> +++ b/libavformat/rmdec.c
> @@ -223,7 +223,7 @@ static int rm_read_audio_stream_info(AVFormatContext *s, AVIOContext *pb,
>                  if (version == 5)
>                      avio_r8(pb);
>                  codecdata_length = avio_rb32(pb);
> -                if(codecdata_length + AV_INPUT_BUFFER_PADDING_SIZE <= (unsigned)codecdata_length){
> +                if(codecdata_length < 0 || codecdata_length > INT_MAX - AV_INPUT_BUFFER_PADDING_SIZE){
>                      av_log(s, AV_LOG_ERROR, "codecdata_length too large\n");
>                      return -1;
>                  }
> 
The first of these checks can be avoided by making codecdata_length
unsigned.

- Andreas
Michael Niedermayer Feb. 16, 2021, 5:57 p.m. UTC | #2 
On Mon, Feb 15, 2021 at 09:38:44PM +0100, Andreas Rheinhardt wrote:
> Michael Niedermayer:
> > Fixes: signed integer overflow: 2147483647 + 64 cannot be represented in type 'int'
> > Fixes: 30333/clusterfuzz-testcase-minimized-ffmpeg_dem_RM_fuzzer-5175286983426048
> > 
> > Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
> > Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
> > ---
> >  libavformat/rmdec.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/libavformat/rmdec.c b/libavformat/rmdec.c
> > index 521b9d0e8c..613fb407df 100644
> > --- a/libavformat/rmdec.c
> > +++ b/libavformat/rmdec.c
> > @@ -223,7 +223,7 @@ static int rm_read_audio_stream_info(AVFormatContext *s, AVIOContext *pb,
> >                  if (version == 5)
> >                      avio_r8(pb);
> >                  codecdata_length = avio_rb32(pb);
> > -                if(codecdata_length + AV_INPUT_BUFFER_PADDING_SIZE <= (unsigned)codecdata_length){
> > +                if(codecdata_length < 0 || codecdata_length > INT_MAX - AV_INPUT_BUFFER_PADDING_SIZE){
> >                      av_log(s, AV_LOG_ERROR, "codecdata_length too large\n");
> >                      return -1;
> >                  }
> > 
> The first of these checks can be avoided by making codecdata_length
> unsigned.

will apply unsigned style check

thx

[...]
diff mbox series

Patch

diff --git a/libavformat/rmdec.c b/libavformat/rmdec.c
index 521b9d0e8c..613fb407df 100644
--- a/libavformat/rmdec.c
+++ b/libavformat/rmdec.c
@@ -223,7 +223,7 @@  static int rm_read_audio_stream_info(AVFormatContext *s, AVIOContext *pb,
                 if (version == 5)
                     avio_r8(pb);
                 codecdata_length = avio_rb32(pb);
-                if(codecdata_length + AV_INPUT_BUFFER_PADDING_SIZE <= (unsigned)codecdata_length){
+                if(codecdata_length < 0 || codecdata_length > INT_MAX - AV_INPUT_BUFFER_PADDING_SIZE){
                     av_log(s, AV_LOG_ERROR, "codecdata_length too large\n");
                     return -1;
                 }