Re: [FFmpeg-devel] [PATCH] tools: Add target_sws_fuzzer.c

[James Almer <jamrial@gmail.com>]

On 2/17/2024 8:48 PM, Michael Niedermayer wrote:
> Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
> ---
>   Makefile                  |   3 +
>   tools/Makefile            |   3 +
>   tools/target_sws_fuzzer.c | 168 ++++++++++++++++++++++++++++++++++++++
>   3 files changed, 174 insertions(+)
>   create mode 100644 tools/target_sws_fuzzer.c
> 
> diff --git a/Makefile b/Makefile
> index dbc930270b3..b309dbc4db9 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -64,6 +64,9 @@ tools/target_dem_fuzzer$(EXESUF): tools/target_dem_fuzzer.o $(FF_DEP_LIBS)
>   tools/target_io_dem_fuzzer$(EXESUF): tools/target_io_dem_fuzzer.o $(FF_DEP_LIBS)
>   	$(LD) $(LDFLAGS) $(LDEXEFLAGS) $(LD_O) $^ $(ELIBS) $(FF_EXTRALIBS) $(LIBFUZZER_PATH)
>   
> +tools/target_sws_fuzzer$(EXESUF): tools/target_sws_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 dee6a416688..72e8e709a8d 100644
> --- a/tools/Makefile
> +++ b/tools/Makefile
> @@ -17,6 +17,9 @@ tools/target_dem_fuzzer.o: tools/target_dem_fuzzer.c
>   tools/target_io_dem_fuzzer.o: tools/target_dem_fuzzer.c
>   	$(COMPILE_C) -DIO_FLAT=0
>   
> +tools/target_sws_fuzzer.o: tools/target_sws_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_sws_fuzzer.c b/tools/target_sws_fuzzer.c
> new file mode 100644
> index 00000000000..babb6e81629
> --- /dev/null
> +++ b/tools/target_sws_fuzzer.c
> @@ -0,0 +1,168 @@
> +/*
> + * 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/opt.h"
> +
> +#include "libavcodec/bytestream.h"
> +
> +#include "libswscale/swscale.h"
> +
> +
> +int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size);
> +
> +static void error(const char *err)
> +{
> +    fprintf(stderr, "%s", err);
> +    exit(1);
> +}
> +
> +static int alloc_plane(uint8_t *data[AV_VIDEO_MAX_PLANES], int stride[AV_VIDEO_MAX_PLANES], int w, int h, int format, int *hshift, int *vshift)
> +{
> +    int ret = av_image_fill_linesizes(stride, format, w);
> +    if (ret < 0)
> +        return -1;
> +
> +    av_pix_fmt_get_chroma_sub_sample(format, hshift, vshift);
> +
> +    for(int p=0; p<AV_VIDEO_MAX_PLANES; p++) {
> +        if (stride[p]) {
> +            stride[p] = FFALIGN(stride[p], 32);
> +            int ph = AV_CEIL_RSHIFT(h, (p == 1 || p == 2) ? *vshift : 0);
> +            av_log(0,0, "P:%d St %d ph %d\n", p, stride[p], ph);
> +            data[p] = av_mallocz(stride[p] * ph + 32);
> +            if (!data[p])
> +                return -1;
> +        }
> +    }
> +    if (format == AV_PIX_FMT_PAL8) {
> +        data[1] = av_mallocz(256*4);
> +        if (!data[1])
> +            return -1;
> +    }
> +    return 0;

av_image_alloc()? Would be better to actually test sws with buffers 
created by our own public helpers.

> +}
> +
> +static void free_plane(uint8_t *data[AV_VIDEO_MAX_PLANES])
> +{
> +    for(int p=0; p<AV_VIDEO_MAX_PLANES; p++)
> +        av_freep(&data[p]);
> +}
> +
> +int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
> +    int srcW= 48, srcH = 48;
> +    int dstW= 48, dstH = 48;
> +    int srcHShift, srcVShift;
> +    int dstHShift, dstVShift;
> +    unsigned flags = 1;
> +    int srcStride[AV_VIDEO_MAX_PLANES] = {0};
> +    int dstStride[AV_VIDEO_MAX_PLANES] = {0};
> +    int ret;
> +    const uint8_t *end = data + size;
> +    enum AVPixelFormat srcFormat = AV_PIX_FMT_YUV420P;
> +    enum AVPixelFormat dstFormat = AV_PIX_FMT_YUV420P;
> +    uint8_t *src[4] = { 0 };
> +    uint8_t *dst[4] = { 0 };

AV_VIDEO_MAX_PLANES.

> +    struct SwsContext *sws = NULL;
> +    const AVPixFmtDescriptor *desc_src, *desc_dst;
> +
> +    if (size > 128) {
> +        GetByteContext gbc;
> +        int64_t flags64;
> +
> +        size -= 128;
> +        bytestream2_init(&gbc, data + size, 128);
> +        srcW = bytestream2_get_le32(&gbc) % 256;
> +        srcH = bytestream2_get_le32(&gbc) % 256;
> +        dstW = bytestream2_get_le32(&gbc) % 256;
> +        dstH = bytestream2_get_le32(&gbc) % 256;
> +        flags = bytestream2_get_le32(&gbc);
> +
> +        srcFormat = bytestream2_get_le32(&gbc) % AV_PIX_FMT_NB;
> +        dstFormat = bytestream2_get_le32(&gbc) % AV_PIX_FMT_NB;

nit: Maybe sanitize the choices with sws_isSupportedInput() and 
sws_isSupportedOutput()? Unless having sws_init_context() fail with 
invalid arguments is also intended.

> +
> +        flags64 = bytestream2_get_le64(&gbc);
> +        if (flags64 & 0x10)
> +            av_force_cpu_flags(0);
> +
> +        if (av_image_check_size(srcW, srcH, srcFormat, NULL))
> +            srcW = srcH = 123;
> +        if (av_image_check_size(dstW, dstH, dstFormat, NULL))
> +            dstW = dstH = 123;

Is there a format where this could fail, knowing the dimensions are at 
most 255x255?

> +        //TODO alphablend
> +    }
> +
> +    desc_src = av_pix_fmt_desc_get(srcFormat);
> +    desc_dst = av_pix_fmt_desc_get(dstFormat);
> +
> +    ret = alloc_plane(src, srcStride, srcW, srcH, srcFormat, &srcHShift, &srcVShift);
> +    if (ret < 0)
> +        goto end;
> +
> +    ret = alloc_plane(dst, dstStride, dstW, dstH, dstFormat, &dstHShift, &dstVShift);
> +    if (ret < 0)
> +        goto end;
> +
> +
> +    for(int p=0; p<AV_VIDEO_MAX_PLANES; p++) {
> +        int psize = srcStride[p] * AV_CEIL_RSHIFT(srcH, (p == 1 || p == 2) ? srcVShift : 0);
> +        if (psize > size)
> +            psize = size;
> +        if (psize) {
> +            memcpy(src[p], data, psize);
> +            data += psize;
> +            size -= psize;
> +        }
> +    }

av_image_copy(). Or av_image_copy_plane() in a loop if you prefer.

> +
> +    sws = sws_alloc_context();
> +    if (!sws)
> +        error("Failed sws allocation");
> +
> +    av_opt_set_int(sws, "sws_flags",  flags, 0);
> +    av_opt_set_int(sws, "srcw",       srcW, 0);
> +    av_opt_set_int(sws, "srch",       srcH, 0);
> +    av_opt_set_int(sws, "dstw",       dstW, 0);
> +    av_opt_set_int(sws, "dsth",       dstH, 0);
> +    av_opt_set_int(sws, "src_format", srcFormat, 0);
> +    av_opt_set_int(sws, "dst_format", dstFormat, 0);
> +    av_opt_set(sws, "alphablend", "none", 0);
> +
> +    ret = sws_init_context(sws, NULL, NULL);
> +    if (ret < 0)
> +        goto end;
> +
> +    fprintf(stderr, "%d x %d %s -> %d x %d %s\n", srcW, srcH, desc_src->name, dstW, dstH, desc_dst->name);
> +    //TODO Slices
> +    sws_scale(sws, (const uint8_t * const*)src, srcStride, 0, srcH, dst, dstStride);
> +
> +end:
> +    sws_freeContext(sws);
> +
> +    free_plane(src);
> +    free_plane(dst);
> +
> +    return 0;
> +}
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