thanks mataness

vm.c

@@ -332,8 +332,10 @@ copyuvm(pde_t *pgdir, uint sz)
     if((mem = kalloc()) == 0)
       goto bad;
     memmove(mem, (char*)P2V(pa), PGSIZE);
-    if(mappages(d, (void*)i, PGSIZE, V2P(mem), flags) < 0)
+    if(mappages(d, (void*)i, PGSIZE, V2P(mem), flags) < 0) {
+      kfree(mem);
       goto bad;
+    }
   }
   return d;