macOS < 10.14.3 / iOS < 12.1.3 XNU - 'vm_map_copy' Optimization which Requires Atomicity isn't Atomic

/ vmmapcopyininternal in vmmap.c converts a region of a vmmap into "copied in" form, constructing a vmmapcopy structure representing the copied memory which can then be mapped into another vmmap or the same one. The function contains a while loop which walks through each of the vmmapentry...