feat: multi-user system, bug fixes, security & performance fixes, and more

programs/include/montauk/heap.h

@@ -151,6 +151,10 @@ namespace heap_detail {
             g_initialized = true;
         }
 
+        // Guard against overflow: size + Header must not wrap
+        if (size > UINT64_MAX - sizeof(Header) - 15)
+            return nullptr;
+
         uint64_t needed = size + sizeof(Header);
         needed = (needed + 15) & ~15ULL;