Bugfix function signature misreport

mythril/disassembler/disassembly.py

@@ -1,10 +1,12 @@
 """This module contains the class used to represent disassembly code."""
 
+from ast import literal_eval
 from typing import Dict, List, Tuple
 
 from mythril.disassembler import asm
 from mythril.ethereum import util
 from mythril.support.signatures import SignatureDB
+from mythril.support.support_args import args
 
 
 class Disassembly(object):
@@ -42,11 +44,26 @@ def assign_bytecode(self, bytecode):
         jump_table_indices = asm.find_op_code_sequence(
             [("PUSH1", "PUSH2", "PUSH3", "PUSH4"), ("EQ",)], self.instruction_list
         )
+        ignore_false_funcs = args.ignore_false_funcs
+        if ignore_false_funcs is None:
+            ignore_false_funcs = [1, 2, 3, 4]
 
         for index in jump_table_indices:
+            # ignore the default func hashes if ignore_false_funcs is None
+            argument = self.instruction_list[index]["argument"]
+            if isinstance(argument, str):
+                function_hash = literal_eval(argument)
+                if function_hash in ignore_false_funcs:
+                    continue
+            elif isinstance(argument, tuple):
+                function_hash = int.from_bytes(bytes(argument), "big")
+                if function_hash in ignore_false_funcs:
+                    continue
+
             function_hash, jump_target, function_name = get_function_info(
                 index, self.instruction_list, signatures
             )
+
             self.func_hashes.append(function_hash)
             if jump_target is not None and function_name is not None:
                 self.function_name_to_address[function_name] = jump_target

mythril/interfaces/cli.py

@@ -27,6 +27,7 @@
 from mythril.laser.ethereum.transaction.symbolic import ACTORS
 from mythril.mythril import MythrilAnalyzer, MythrilConfig, MythrilDisassembler
 from mythril.plugin.loader import MythrilPluginLoader
+from mythril.support.support_args import args as support_args
 
 # Initialise core Mythril Component
 _ = MythrilPluginLoader()
@@ -470,6 +471,13 @@ def add_analysis_args(options):
         "Like [[func_hash1, func_hash2], [func_hash2, func_hash3]] where the first transaction is constrained "
         "with func_hash1 and func_hash2, and the second tx is constrained with func_hash2 and func_hash3. Use -1 as a proxy for fallback() function and -2 for receive() function.",
     )
+    options.add_argument(
+        "--ignore-false-funcs",
+        type=str,
+        default=None,
+        help="List of function signatures that should be ignored as false positives."
+        "usage: --ignore-false-funcs [func1, func2, ...]",
+    )
     options.add_argument(
         "--beam-search",
         type=int,
@@ -662,6 +670,17 @@ def validate_args(args: Namespace):
         if len(args.transaction_sequences) != args.transaction_count:
             args.transaction_count = len(args.transaction_sequences)
 
+    if getattr(args, "ignore_false_funcs", None):
+        try:
+            args.ignore_false_funcs = literal_eval(str(args.ignore_false_funcs))
+        except ValueError:
+            exit_with_error(
+                args.outform,
+                "The ignore false functions are in incorrect format, It should be "
+                "[func1, func2, ...]. The default ignore false functions are "
+                "[0x00000001, 0x00000002, 0x00000003, 0x00000004]",
+            )
+
 
 def set_config(args: Namespace):
     """
@@ -954,6 +973,7 @@ def parse_args_and_execute(parser: ArgumentParser, args: Namespace) -> None:
         solc_json = getattr(args, "solc_json", None)
         solv = getattr(args, "solv", None)
         solc_args = getattr(args, "solc_args", None)
+        support_args.ignore_false_funcs = getattr(args, "ignore_false_funcs", None)
         disassembler = MythrilDisassembler(
             eth=config.eth,
             solc_version=solv,

mythril/support/support_args.py

@@ -18,6 +18,7 @@ def __init__(self):
         self.disable_iprof = False
         self.solver_log = None
         self.transaction_sequences: List[List[str]] = None
+        self.ignore_false_funcs: List[str] = None
         self.use_integer_module = True
         self.use_issue_annotations = False
         self.solc_args = None

tests/integration_tests/ignore_false_funcs_test.py

@@ -0,0 +1,17 @@
+import pytest
+from utils import output_of
+
+from tests import PROJECT_DIR, TESTDATA
+
+MYTH = str(PROJECT_DIR / "myth")
+
+test_data = [
+    (f"{TESTDATA}/input_contracts/base_case.sol", "0x83197ef0"),
+]
+
+
+@pytest.mark.parametrize("file_name, ignore_func", test_data)
+def test_ignore_false_funcs(file_name, ignore_func):
+    print(file_name)
+    output = output_of(f"{MYTH} a {file_name} --ignore-false-funcs [{ignore_func}]")
+    assert "Function name: destroy()" not in output