max op length assumed

sins/mutation.py

@@ -55,13 +55,20 @@ def generation(queue: Queue, shellcode: bytes):
 
 
 def growth(*, shellcode: bytes, length: int) -> bytes:
-    for mnemonic, op_str in disasm(shellcode):
-        if mnemonic == 'nop':
-            return bytes(shellcode)
-
     if length <= len(shellcode):
         return bytes(shellcode)
 
+    opcodes = disasm(shellcode)
+
+    max_op_len = 15
+
+    if len(shellcode) > len(opcodes) * max_op_len:
+        return bytes(shellcode)
+
+    for mnemonic, op_str in opcodes:
+        if mnemonic == 'nop':
+            return bytes(shellcode)
+
     shellcode = bytearray(shellcode)
     shellcode += b'\x90'