A packet referencing a driver buffer has no AV_INPUT_BUFFER_PADDING_SIZE
Fixes: 7ZY4JenXTFy4
Fixes: out of array read
Out of array read Replicated through UnModified FFmpeg with v4l2loopback and an LD_PRELOAD guard page behind the mmap buffers
Found during the review of https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/24659