Some decoders may not need a writable buffer in some specific cases, but only
a reference to the existing buffer with updated frame properties instead, for
the purpose of returning duplicate frames. For this, the
FF_REGET_BUFFER_FLAG_READONLY flag is added, which will prevent potential
allocations and buffer copies when they are not needed.
Signed-off-by: James Almer <jamrial@gmail.com>

Fixes: out of array read
Fixes: 15982/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_MSA1_fuzzer-5630676251967488

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpegSigned-off-by: Michael Niedermayer <michael@niedermayer.cc>

avcodec/mss3: Fix runtime error: signed integer overflow: -2146318336 - 2139696256 cannot be represented in type 'int'

Fix is similar to rac_get_model_sym()
Fixes: 1483/clusterfuzz-testcase-minimized-6386507814273024
Fixes: 1485/clusterfuzz-testcase-minimized-6639880215986176

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/targets/ffmpegSigned-off-by: Michael Niedermayer <michael@niedermayer.cc>

Fixes integer overflow
Fixes: 1372/clusterfuzz-testcase-minimized-5712192982745088

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/targets/ffmpegSigned-off-by: Michael Niedermayer <michael@niedermayer.cc>

ptrdiff_t is the correct type for array strides and similar.

Express bitfields more simply.
Signed-off-by: Vittorio Giovara <vittorio.giovara@gmail.com>

Signed-off-by: Paul B Mahol <onemda@gmail.com>

Coccinelle profile used:

  @@
  expression r, ctx, f, loglevel, str, flags;
  @@

  -if ((r = ff_get_buffer(ctx, f, flags)) < 0) {
  -    av_log(ctx, loglevel, str);
  -    return r;
  -}
  +if ((r = ff_get_buffer(ctx, f, flags)) < 0)
  +    return r;

  @@
  expression r, ctx, f, loglevel, str;
  @@

  -if ((r = ff_reget_buffer(ctx, f)) < 0) {
  -    av_log(ctx, loglevel, str);
  -    return r;
  -}
  +if ((r = ff_reget_buffer(ctx, f)) < 0)
  +    return r;

  @@
  expression r, ctx, f, loglevel, str, flags;
  @@

  -if ((r = ff_thread_get_buffer(ctx, f, flags)) < 0) {
  -    av_log(ctx, loglevel, str);
  -    return r;
  -}
  +if ((r = ff_thread_get_buffer(ctx, f, flags)) < 0)
  +    return r;

...along with some manual patches for the remaining ones.

Fixes division by zero

Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

It's got_frame, not data size