Merge pull request #1213 from ConsenSys/harvey_style_assertions

Harvey style assertions

docs/source/module-list.rst

@@ -67,3 +67,9 @@ Unchecked Retval
 ****************
 
 The `unchecked retval module <https://github.com/ConsenSys/mythril/blob/develop/mythril/analysis/modules/unchecked_retval.py>`_ detects `SWC-104 (Unchecked Call Return Value) <https://smartcontractsecurity.github.io/SWC-registry/docs/SWC-104>`_.
+
+****************
+Unchecked Retval
+****************
+
+The `user supplied assertion module <https://github.com/ConsenSys/mythril/blob/develop/mythril/analysis/modules/unchecked_retval.py>`_ detects `SWC-110 (Assert Violation) <https://smartcontractsecurity.github.io/SWC-registry/docs/SWC-110>`_ for user-supplied assertions. User supplied assertions should be log messages of the form: :code:`emit AssertionFailed(string)`.

mythril/analysis/modules/user_assertions.py

@@ -0,0 +1,100 @@
+"""This module contains the detection code for potentially insecure low-level
+calls."""
+
+from mythril.analysis.potential_issues import (
+    PotentialIssue,
+    get_potential_issues_annotation,
+)
+from mythril.analysis.swc_data import ASSERT_VIOLATION
+from mythril.analysis.modules.base import DetectionModule
+from mythril.laser.ethereum.state.global_state import GlobalState
+import logging
+import eth_abi
+
+log = logging.getLogger(__name__)
+
+DESCRIPTION = """
+
+Search for reachable user-supplied exceptions.
+Report a warning if an log message is emitted: 'emit AssertionFailed(string)'
+
+"""
+
+assertion_failed_hash = (
+    0xB42604CB105A16C8F6DB8A41E6B00C0C1B4826465E8BC504B3EB3E88B3E6A4A0
+)
+
+
+class UserAssertions(DetectionModule):
+    """This module searches for user supplied exceptions: emit AssertionFailed("Error")."""
+
+    def __init__(self):
+        """"""
+        super().__init__(
+            name="External calls",
+            swc_id=ASSERT_VIOLATION,
+            description=DESCRIPTION,
+            entrypoint="callback",
+            pre_hooks=["LOG1"],
+        )
+
+    def _execute(self, state: GlobalState) -> None:
+        """
+
+        :param state:
+        :return:
+        """
+        potential_issues = self._analyze_state(state)
+
+        annotation = get_potential_issues_annotation(state)
+        annotation.potential_issues.extend(potential_issues)
+
+    def _analyze_state(self, state: GlobalState):
+        """
+
+        :param state:
+        :return:
+        """
+        topic, size, mem_start = state.mstate.stack[-3:]
+
+        if topic.symbolic or topic.value != assertion_failed_hash:
+            return []
+
+        message = None
+        if not mem_start.symbolic and not size.symbolic:
+            message = eth_abi.decode_single(
+                "string",
+                bytes(
+                    state.mstate.memory[
+                        mem_start.value + 32 : mem_start.value + size.value
+                    ]
+                ),
+            ).decode("utf8")
+
+        description_head = "A user-provided assertion failed."
+        if message:
+            description_tail = "A user-provided assertion failed with message '{}'. Make sure the user-provided assertion is correct.".format(
+                message
+            )
+        else:
+            description_tail = "A user-provided assertion failed. Make sure the user-provided assertion is correct."
+
+        address = state.get_current_instruction()["address"]
+        issue = PotentialIssue(
+            contract=state.environment.active_account.contract_name,
+            function_name=state.environment.active_function_name,
+            address=address,
+            swc_id=ASSERT_VIOLATION,
+            title="Assertion Failed",
+            bytecode=state.environment.code.bytecode,
+            severity="Medium",
+            description_head=description_head,
+            description_tail=description_tail,
+            constraints=[],
+            detector=self,
+        )
+
+        return [issue]
+
+
+detector = UserAssertions()