Re: [FFmpeg-devel] [PATCH v2] add tools/target_swr_fuzzer

[Michael Niedermayer <michael@niedermayer.cc>]

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On Wed, Aug 07, 2024 at 04:02:23PM -0300, James Almer wrote:
> On 8/7/2024 2:13 PM, Michael Niedermayer wrote:
> > On Wed, Aug 07, 2024 at 01:05:40PM -0300, James Almer wrote:
> > > 
> > > 
> > > On 8/7/2024 12:51 PM, Michael Niedermayer wrote:
> > > > Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
> > > > ---
> > > >    Makefile                  |   2 +
> > > >    tools/Makefile            |   3 +
> > > >    tools/target_swr_fuzzer.c | 150 ++++++++++++++++++++++++++++++++++++++
> > > >    3 files changed, 155 insertions(+)
> > > >    create mode 100644 tools/target_swr_fuzzer.c
> > > > 
> > > > diff --git a/Makefile b/Makefile
> > > > index 4c3af09fec4..b350d7748f5 100644
> > > > --- a/Makefile
> > > > +++ b/Makefile
> > > > @@ -70,6 +70,8 @@ tools/target_io_dem_fuzzer$(EXESUF): tools/target_io_dem_fuzzer.o $(FF_DEP_LIBS)
> > > >    tools/target_sws_fuzzer$(EXESUF): tools/target_sws_fuzzer.o $(FF_DEP_LIBS)
> > > >    	$(LD) $(LDFLAGS) $(LDEXEFLAGS) $(LD_O) $^ $(ELIBS) $(FF_EXTRALIBS) $(LIBFUZZER_PATH)
> > > > +tools/target_swr_fuzzer$(EXESUF): tools/target_swr_fuzzer.o $(FF_DEP_LIBS)
> > > > +	$(LD) $(LDFLAGS) $(LDEXEFLAGS) $(LD_O) $^ $(ELIBS) $(FF_EXTRALIBS) $(LIBFUZZER_PATH)
> > > >    tools/enum_options$(EXESUF): ELIBS = $(FF_EXTRALIBS)
> > > >    tools/enum_options$(EXESUF): $(FF_DEP_LIBS)
> > > > diff --git a/tools/Makefile b/tools/Makefile
> > > > index 2a11fa0ae62..7ae6e3cb75d 100644
> > > > --- a/tools/Makefile
> > > > +++ b/tools/Makefile
> > > > @@ -23,6 +23,9 @@ tools/target_io_dem_fuzzer.o: tools/target_dem_fuzzer.c
> > > >    tools/target_sws_fuzzer.o: tools/target_sws_fuzzer.c
> > > >    	$(COMPILE_C)
> > > > +tools/target_swr_fuzzer.o: tools/target_swr_fuzzer.c
> > > > +	$(COMPILE_C)
> > > > +
> > > >    tools/enc_recon_frame_test$(EXESUF): tools/decode_simple.o
> > > >    tools/venc_data_dump$(EXESUF): tools/decode_simple.o
> > > >    tools/scale_slice_test$(EXESUF): tools/decode_simple.o
> > > > diff --git a/tools/target_swr_fuzzer.c b/tools/target_swr_fuzzer.c
> > > > new file mode 100644
> > > > index 00000000000..b8af0bad78c
> > > > --- /dev/null
> > > > +++ b/tools/target_swr_fuzzer.c
> > > > @@ -0,0 +1,150 @@
> > > > +/*
> > > > + * Copyright (c) 2024 Michael Niedermayer <michael-ffmpeg@niedermayer.cc>
> > > > + *
> > > > + * This file is part of FFmpeg.
> > > > + *
> > > > + * FFmpeg is free software; you can redistribute it and/or
> > > > + * modify it under the terms of the GNU Lesser General Public
> > > > + * License as published by the Free Software Foundation; either
> > > > + * version 2.1 of the License, or (at your option) any later version.
> > > > + *
> > > > + * FFmpeg is distributed in the hope that it will be useful,
> > > > + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> > > > + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> > > > + * Lesser General Public License for more details.
> > > > + *
> > > > + * You should have received a copy of the GNU Lesser General Public
> > > > + * License along with FFmpeg; if not, write to the Free Software
> > > > + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
> > > > + */
> > > > +
> > > > +#include "config.h"
> > > > +#include "libavutil/avassert.h"
> > > > +#include "libavutil/avstring.h"
> > > > +#include "libavutil/cpu.h"
> > > > +#include "libavutil/imgutils.h"
> > > > +#include "libavutil/intreadwrite.h"
> > > > +#include "libavutil/mem.h"
> > > > +#include "libavutil/opt.h"
> > > > +
> > > > +#include "libavcodec/bytestream.h"
> > > > +
> > > > +#include "libswresample/swresample.h"
> > > > +
> > > > +#define SWR_CH_MAX 32
> > > > +
> > > > +int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size);
> > > > +
> > > > +static const enum AVSampleFormat formats[] = {
> > > > +    AV_SAMPLE_FMT_U8,
> > > > +    AV_SAMPLE_FMT_U8P,
> > > > +    AV_SAMPLE_FMT_S16,
> > > > +    AV_SAMPLE_FMT_S16P,
> > > > +    AV_SAMPLE_FMT_S32,
> > > > +    AV_SAMPLE_FMT_S32P,
> > > > +    AV_SAMPLE_FMT_FLT,
> > > > +    AV_SAMPLE_FMT_FLTP,
> > > > +    AV_SAMPLE_FMT_DBL,
> > > > +    AV_SAMPLE_FMT_DBLP,
> > > > +};
> > > > +
> > > > +static const AVChannelLayout layouts[]={
> > > > +    AV_CHANNEL_LAYOUT_MONO               ,
> > > > +    AV_CHANNEL_LAYOUT_STEREO             ,
> > > > +    AV_CHANNEL_LAYOUT_2_1                ,
> > > > +    AV_CHANNEL_LAYOUT_SURROUND           ,
> > > > +    AV_CHANNEL_LAYOUT_4POINT0            ,
> > > > +    AV_CHANNEL_LAYOUT_2_2                ,
> > > > +    AV_CHANNEL_LAYOUT_QUAD               ,
> > > > +    AV_CHANNEL_LAYOUT_5POINT0            ,
> > > > +    AV_CHANNEL_LAYOUT_5POINT1            ,
> > > > +    AV_CHANNEL_LAYOUT_5POINT0_BACK       ,
> > > > +    AV_CHANNEL_LAYOUT_5POINT1_BACK       ,
> > > > +    AV_CHANNEL_LAYOUT_7POINT0            ,
> > > > +    AV_CHANNEL_LAYOUT_7POINT1            ,
> > > > +    AV_CHANNEL_LAYOUT_7POINT1_WIDE       ,
> > > > +    AV_CHANNEL_LAYOUT_22POINT2           ,
> > > > +    AV_CHANNEL_LAYOUT_5POINT1POINT2_BACK ,
> > > 
> > > Maybe also AV_CHANNEL_LAYOUT_22POINT2 to ensure the fallback to 7.1(wide)+BC
> > > in rematrix.c works as intended.
> > 
> > added with my time-machiene, can you confirm its in the mail i sent before
> > your reply ?
> 
> I'm blind, disregard this.
> 
> > 
> > 
> > > 
> > > > +};
> > > > +
> > > > +int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
> > > > +    const uint8_t *end = data + size;
> > > > +    struct SwrContext * swr= NULL;
> > > > +    AVChannelLayout in_ch_layout = { 0 }, out_ch_layout = { 0 };
> > > > +    enum AVSampleFormat  in_sample_fmt = AV_SAMPLE_FMT_S16P;
> > > > +    enum AVSampleFormat out_sample_fmt = AV_SAMPLE_FMT_S16P;
> > > > +    int  in_sample_rate = 44100;
> > > > +    int out_sample_rate = 44100;
> > > > +    int in_ch_count, out_ch_count;
> > > > +    char  in_layout_string[256];
> > > > +    char out_layout_string[256];
> > > > +    uint8_t * ain[SWR_CH_MAX];
> > > > +    uint8_t *aout[SWR_CH_MAX];
> > > > +    uint8_t *out_data;
> > > > +    int in_sample_nb;
> > > > +    int out_sample_nb = size;
> > > > +    int count;
> > > > +
> > > > +    if (size > 128) {
> > > > +        GetByteContext gbc;
> > > > +        int64_t flags64;
> > > > +
> > > > +        size -= 128;
> > > > +        bytestream2_init(&gbc, data + size, 128);
> > > > +         in_sample_rate = bytestream2_get_le16(&gbc) + 1;
> > > > +        out_sample_rate = bytestream2_get_le16(&gbc) + 1;
> > > > +         in_sample_fmt  = formats[bytestream2_get_byte(&gbc) % FF_ARRAY_ELEMS(formats)];
> > > > +        out_sample_fmt  = formats[bytestream2_get_byte(&gbc) % FF_ARRAY_ELEMS(formats)];
> > > > +        av_channel_layout_copy(& in_ch_layout,  &layouts[bytestream2_get_byte(&gbc) % FF_ARRAY_ELEMS(layouts)]);
> > > > +        av_channel_layout_copy(&out_ch_layout,  &layouts[bytestream2_get_byte(&gbc) % FF_ARRAY_ELEMS(layouts)]);
> > > 
> > > Since you're only using native layouts, you could make the layouts array be
> > > of uint64_t masks (AV_CH_LAYOUT_*) and use av_channel_layout_from_mask()
> > > here.
> > 
> > I still refuse to do this because the fuzzer should have maximal coverage
> > and limiting things to subsets goes against that idea even if the current
> > code is limited to a subset
> > 
> > Maybe iam missing something of course, but it simply doesnt seem the right
> > direction
> 
> You're not really testing any fuzzed input whatsoever here because you're
> passing strictly supported values to av_channel_layout_copy().

The thing is, we could pass layouts that are not represented by a 64bit mask


> The difference in using av_channel_layout_from_mask() is that it should be
> slightly faster (No uninit() call and no copy of the entire struct, setting
> only the three fields that matter).
> 
> But it's mostly a nit too, so it's fine as is if you prefer it.

yes i prefer this unless theres a reason why we could never ever extend
this beyond layouts represented by 64bit masks

thx

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Those who are too smart to engage in politics are punished by being
governed by those who are dumber. -- Plato 

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