map: fix mprotected pages not being copied

When a memory region with prot read-write got changed to read, then the
memory would not be copied on fork. This result in child and parent
sharing this page that can be changed back to being writeable.

JIRA: RTOS-953

vm/map.c

@@ -879,6 +879,10 @@ int vm_mprotect(vm_map_t *map, void *vaddr, size_t len, int prot)
 			e->prot = prot;
 
 			attr = vm_protToAttr(e->prot) | vm_flagsToAttr(e->flags);
+			/* If an entry needs copy, enter it as a readonly to copy it on first access. */
+			if ((e->flags & MAP_NEEDSCOPY) != 0) {
+				attr &= ~(vm_protToAttr(PROT_WRITE));
+			}
 			for (currVaddr = e->vaddr; currVaddr < (e->vaddr + e->size); currVaddr += SIZE_PAGE) {
 				pa = pmap_resolve(&map->pmap, currVaddr);
 				if (pa != 0) {
@@ -1048,7 +1052,7 @@ int vm_mapCopy(process_t *proc, vm_map_t *dst, vm_map_t *src)
 		vm_mapEntryCopy(f, e, 1);
 		_map_add(proc, dst, f);
 
-		if (((e->prot & PROT_WRITE) != 0) && ((e->flags & MAP_DEVICE) == 0)) {
+		if (((e->protOrig & PROT_WRITE) != 0) && ((e->flags & MAP_DEVICE) == 0)) {
 			e->flags |= MAP_NEEDSCOPY;
 			f->flags |= MAP_NEEDSCOPY;