[FFmpeg-devel] [PATCH 1/4] avcodec/mpegaudiodec_template: use unsigned shift in handle_crc()

[FFmpeg-devel] [PATCH 1/4] avcodec/mpegaudiodec_template: use unsigned shift in handle_crc()

[Michael Niedermayer]

Fixes: left shift of 192 by 24 places cannot be represented in type 'int'
Fixes: 49577/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_MP1FLOAT_fuzzer-5205996678545408

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

diff --git a/libavcodec/mpegaudiodec_template.c b/libavcodec/mpegaudiodec_template.c
index a28cac9867..a711154a3c 100644
--- a/libavcodec/mpegaudiodec_template.c
+++ b/libavcodec/mpegaudiodec_template.c
@@ -374,7 +374,7 @@ static int handle_crc(MPADecodeContext *s, int sec_len)
         crc_val = av_crc(crc_tab, crc_val, &buf[6], sec_byte_len);
 
         AV_WB32(tmp_buf,
-                ((buf[6 + sec_byte_len] & (0xFF00 >> sec_rem_bits)) << 24) +
+                ((buf[6 + sec_byte_len] & (0xFF00U >> sec_rem_bits)) << 24) +
                 ((s->crc << 16) >> sec_rem_bits));
 
         crc_val = av_crc(crc_tab, crc_val, tmp_buf, 3);
-- 
2.17.1

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[FFmpeg-devel] [PATCH 2/4] avcodec/hevcdec: Check s->ref in the md5 path similar to hwaccel

[Michael Niedermayer]

This is somewhat redundant with the is_decoded check. Maybe
there is a nicer solution

Fixes: Null pointer dereference
Fixes: 49584/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_HEVC_fuzzer-5297367351427072

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

diff --git a/libavcodec/hevcdec.c b/libavcodec/hevcdec.c
index f1be8af2cd..477d6d9d36 100644
--- a/libavcodec/hevcdec.c
+++ b/libavcodec/hevcdec.c
@@ -3498,7 +3498,7 @@ static int hevc_decode_frame(AVCodecContext *avctx, AVFrame *rframe,
         }
     } else {
         /* verify the SEI checksum */
-        if (avctx->err_recognition & AV_EF_CRCCHECK && s->is_decoded &&
+        if (avctx->err_recognition & AV_EF_CRCCHECK && s->ref && s->is_decoded &&
             s->sei.picture_hash.is_md5) {
             ret = verify_md5(s, s->ref->frame);
             if (ret < 0 && avctx->err_recognition & AV_EF_EXPLODE) {
-- 
2.17.1

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[FFmpeg-devel] [PATCH 3/4] avcodec/h263dec: Sanity check against minimal I/P frame size

[Michael Niedermayer]

Fixes: Timeout
Fixes: 49718/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_MPEG4_fuzzer-4874987894341632

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
---
 libavcodec/h263dec.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/libavcodec/h263dec.c b/libavcodec/h263dec.c
index 8db0eccd89..c03a55a4fd 100644
--- a/libavcodec/h263dec.c
+++ b/libavcodec/h263dec.c
@@ -553,6 +553,8 @@ retry:
     avctx->has_b_frames = !s->low_delay;
 
     if (CONFIG_MPEG4_DECODER && avctx->codec_id == AV_CODEC_ID_MPEG4) {
+        if (s->pict_type != AV_PICTURE_TYPE_B && s->mb_num/2 > get_bits_count(&s->gb))
+            return AVERROR_INVALIDDATA;
         if (ff_mpeg4_workaround_bugs(avctx) == 1)
             goto retry;
         if (s->studio_profile != (s->idsp.idct == NULL))
-- 
2.17.1

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Re: [FFmpeg-devel] [PATCH 3/4] avcodec/h263dec: Sanity check against minimal I/P frame size

[Andreas Rheinhardt]

Michael Niedermayer:
> Fixes: Timeout
> Fixes: 49718/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_MPEG4_fuzzer-4874987894341632
> 
> Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
> Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
> ---
>  libavcodec/h263dec.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/libavcodec/h263dec.c b/libavcodec/h263dec.c
> index 8db0eccd89..c03a55a4fd 100644
> --- a/libavcodec/h263dec.c
> +++ b/libavcodec/h263dec.c
> @@ -553,6 +553,8 @@ retry:
>      avctx->has_b_frames = !s->low_delay;
>  
>      if (CONFIG_MPEG4_DECODER && avctx->codec_id == AV_CODEC_ID_MPEG4) {
> +        if (s->pict_type != AV_PICTURE_TYPE_B && s->mb_num/2 > get_bits_count(&s->gb))
> +            return AVERROR_INVALIDDATA;
>          if (ff_mpeg4_workaround_bugs(avctx) == 1)
>              goto retry;
>          if (s->studio_profile != (s->idsp.idct == NULL))

Is it possible that you wanted to use get_bits_left() here?

- Andreas
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Re: [FFmpeg-devel] [PATCH 3/4] avcodec/h263dec: Sanity check against minimal I/P frame size

[Michael Niedermayer]

[-- Attachment #1.1: Type: text/plain, Size: 1432 bytes --]

On Mon, Aug 15, 2022 at 09:04:09PM +0200, Andreas Rheinhardt wrote:
> Michael Niedermayer:
> > Fixes: Timeout
> > Fixes: 49718/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_MPEG4_fuzzer-4874987894341632
> > 
> > Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
> > Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
> > ---
> >  libavcodec/h263dec.c | 2 ++
> >  1 file changed, 2 insertions(+)
> > 
> > diff --git a/libavcodec/h263dec.c b/libavcodec/h263dec.c
> > index 8db0eccd89..c03a55a4fd 100644
> > --- a/libavcodec/h263dec.c
> > +++ b/libavcodec/h263dec.c
> > @@ -553,6 +553,8 @@ retry:
> >      avctx->has_b_frames = !s->low_delay;
> >  
> >      if (CONFIG_MPEG4_DECODER && avctx->codec_id == AV_CODEC_ID_MPEG4) {
> > +        if (s->pict_type != AV_PICTURE_TYPE_B && s->mb_num/2 > get_bits_count(&s->gb))
> > +            return AVERROR_INVALIDDATA;
> >          if (ff_mpeg4_workaround_bugs(avctx) == 1)
> >              goto retry;
> >          if (s->studio_profile != (s->idsp.idct == NULL))
> 
> Is it possible that you wanted to use get_bits_left() here?

yes 

thx


[...]
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Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

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of what is before them, glory and danger alike, and yet
notwithstanding go out to meet it. -- Thucydides

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[FFmpeg-devel] [PATCH 4/4] tools/target_dec_fuzzer: Adjust threshold for ZLIB

[Michael Niedermayer]

Fixes: Timeout
Fixes: 49769/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_ZLIB_fuzzer-6302938657587200

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

diff --git a/tools/target_dec_fuzzer.c b/tools/target_dec_fuzzer.c
index e1b5d2b3c1..28042077c6 100644
--- a/tools/target_dec_fuzzer.c
+++ b/tools/target_dec_fuzzer.c
@@ -298,6 +298,7 @@ int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
     case AV_CODEC_ID_WMALOSSLESS: maxsamples /= 1024;  break;
     case AV_CODEC_ID_YLC:         maxpixels  /= 1024;  break;
     case AV_CODEC_ID_ZEROCODEC:   maxpixels  /= 128;   break;
+    case AV_CODEC_ID_ZLIB:        maxpixels  /= 4096;  break;
     }
 
     maxsamples_per_frame = FFMIN(maxsamples_per_frame, maxsamples);
-- 
2.17.1

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Re: [FFmpeg-devel] [PATCH 1/4] avcodec/mpegaudiodec_template: use unsigned shift in handle_crc()

[Michael Niedermayer]

[-- Attachment #1.1: Type: text/plain, Size: 702 bytes --]

On Mon, Aug 15, 2022 at 07:59:24PM +0200, Michael Niedermayer wrote:
> Fixes: left shift of 192 by 24 places cannot be represented in type 'int'
> Fixes: 49577/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_MP1FLOAT_fuzzer-5205996678545408
> 
> Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
> Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
> ---
>  libavcodec/mpegaudiodec_template.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)

will apply patchset with the typo fixed

[...]
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You can kill me, but you cannot change the truth.

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