Stack overflow errors are not funny. Can you try to locate the test that causes it?
Without either of the memory test loops I can now (after the recursive lock fix) run all tests successfully. The first memory test gives 400 failures:
[FAIL] p = (void*)_shoot_malloc(24*1024*1024) => 0x0
[FAIL] UNCACHEABLE(p) => 0x40000000
Reducing that allocation size to 20 megs or switching the camera to small JPEG makes it work. Debug menu gives maximum contiguous block as 20MB with my normal RAW settings, 29 megs with S3 JPEG.
The second memory test loop partially hangs camera, doesn't give the stack overflow now, camera can be shut down, but leaves the led on, I'll double check the stubs just in case and add some more prints.