Adds appropriate checks/guards around all the untrusted parameters
which are used for reading from memory.
Validation:
- All the crashing files within the bug have been checked to not causes
crashes any longer>
- A handful of correct .bmp were validated: 3 different files at each
of 1, 4, 8, 24, 32 bpp depth along with a random variety of other 24
bpp files (around 20 in total).
- ~280 million iterations of fuzzing using AFL were completed with 0
crashes. The old code experienced several dozen crashes in first
minutes of running {F8584509}.
Ref D7945
5b08cbae51