svc: Add missing sanitizing checks for MapSharedMemory/UnmapSharedMemory

Now that the changes clarifying the address spaces has been merged, we
can wrap the checks that the kernel performs when mapping shared memory
(and other forms of memory) into its own helper function and then use
those within MapSharedMemory and UnmapSharedMemory to complete the
sanitizing checks that are supposed to be done.

src/core/hle/kernel/vm_manager.cpp

@@ -507,6 +507,26 @@ u64 VMManager::GetASLRRegionSize() const {
     return aslr_region_end - aslr_region_base;
 }
 
+bool VMManager::IsWithinASLRRegion(VAddr begin, u64 size) const {
+    const VAddr range_end = begin + size;
+    const VAddr aslr_start = GetASLRRegionBaseAddress();
+    const VAddr aslr_end = GetASLRRegionEndAddress();
+
+    if (aslr_start > begin || begin > range_end || range_end - 1 > aslr_end - 1) {
+        return false;
+    }
+
+    if (range_end > heap_region_base && heap_region_end > begin) {
+        return false;
+    }
+
+    if (range_end > map_region_base && map_region_end > begin) {
+        return false;
+    }
+
+    return true;
+}
+
 VAddr VMManager::GetCodeRegionBaseAddress() const {
     return code_region_base;
 }