[FFmpeg-devel] [PATCH] tools/target_dec_fuzzer: set request_channel_layout

[Michael Niedermayer]

On Fri, Dec 06, 2019 at 11:56:13AM -0300, James Almer wrote:
> Should increase coverage of some decoders.
> 
> Signed-off-by: James Almer <jamrial at gmail.com>
> ---
> Passing 6 to av_get_default_channel_layout() will return the 5.1 layout but
> never 5.1(side), which is for example what the dts decoder actually looks for.
> Any suggestion on how to make the fuzzer pick one of the non default layouts
> using a given amount of channels?

did you try:

diff --git a/tools/target_dec_fuzzer.c b/tools/target_dec_fuzzer.c
index 691a79329f..d53dccdcf5 100644
--- a/tools/target_dec_fuzzer.c
+++ b/tools/target_dec_fuzzer.c
@@ -212,6 +212,7 @@ int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
         ctx->codec_tag                          = bytestream2_get_le32(&gbc);
         keyframes                               = bytestream2_get_le64(&gbc);
         flushpattern                            = bytestream2_get_le64(&gbc);
+        ctx->request_channel_layout             = bytestream2_get_le64(&gbc);
 
         if (extradata_size < size) {
             ctx->extradata = av_mallocz(extradata_size + AV_INPUT_BUFFER_PADDING_SIZE);



> 
>  tools/target_dec_fuzzer.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/tools/target_dec_fuzzer.c b/tools/target_dec_fuzzer.c
> index dcf47b0f4d..fbfbbbc7ac 100644
> --- a/tools/target_dec_fuzzer.c
> +++ b/tools/target_dec_fuzzer.c
> @@ -47,6 +47,7 @@
>  
>  #include "config.h"
>  #include "libavutil/avassert.h"
> +#include "libavutil/channel_layout.h"
>  #include "libavutil/imgutils.h"
>  #include "libavutil/intreadwrite.h"
>  
> @@ -207,6 +208,7 @@ int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
>  
>          ctx->sample_rate                        = bytestream2_get_le32(&gbc);
>          ctx->channels                           = (unsigned)bytestream2_get_le32(&gbc) % FF_SANE_NB_CHANNELS;
> +        ctx->request_channel_layout             = av_get_default_channel_layout((unsigned)bytestream2_get_le32(&gbc) % FF_SANE_NB_CHANNELS);
>          ctx->block_align                        = bytestream2_get_le32(&gbc);
>          ctx->codec_tag                          = bytestream2_get_le32(&gbc);
>          keyframes                               = bytestream2_get_le64(&gbc);


Its better to add reading at the end so as to minimize disruption to existing
testcases

Thanks

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

Opposition brings concord. Out of discord comes the fairest harmony.
-- Heraclitus
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