Merge pull request #1891 from crytic/fp/incorrect-shift

do not detect incorrect-shift when rhs is constant
crytic · May 5, 2023 · c1ae06a · c1ae06a
2 parents df0b7ce + e42408b
commit c1ae06a
Show file tree

Hide file tree

Showing 4 changed files with 6 additions and 3 deletions.
diff --git a/slither/detectors/assembly/shift_parameter_mixup.py b/slither/detectors/assembly/shift_parameter_mixup.py
@@ -52,7 +52,9 @@ def _check_function(self, f: FunctionContract) -> List[Output]:
                     BinaryType.LEFT_SHIFT,
                     BinaryType.RIGHT_SHIFT,
                 ]:
-                    if isinstance(ir.variable_left, Constant):
+                    if isinstance(ir.variable_left, Constant) and not isinstance(
+                        ir.variable_right, Constant
+                    ):
                         info: DETECTOR_INFO = [
                             f,
                             " contains an incorrect shift operation: ",

diff --git a/.../snapshots/detectors__detector_ShiftParameterMixup_0_7_6_shift_parameter_mixup_sol__0.txt b/.../snapshots/detectors__detector_ShiftParameterMixup_0_7_6_shift_parameter_mixup_sol__0.txt
@@ -1,2 +1,2 @@
-C.f() (tests/e2e/detectors/test_data/incorrect-shift/0.7.6/shift_parameter_mixup.sol#3-7) contains an incorrect shift operation: a = 8 >> a (tests/e2e/detectors/test_data/incorrect-shift/0.7.6/shift_parameter_mixup.sol#5)
+C.f() (tests/e2e/detectors/test_data/incorrect-shift/0.7.6/shift_parameter_mixup.sol#3-8) contains an incorrect shift operation: a = 8 >> a (tests/e2e/detectors/test_data/incorrect-shift/0.7.6/shift_parameter_mixup.sol#5)
 
diff --git a/tests/e2e/detectors/test_data/incorrect-shift/0.7.6/shift_parameter_mixup.sol b/tests/e2e/detectors/test_data/incorrect-shift/0.7.6/shift_parameter_mixup.sol
@@ -1,8 +1,9 @@
 contract C { 
 
-    function f() internal returns (uint a) { 
+    function f() internal returns (uint a, uint b) { 
         assembly { 
             a := shr(a, 8) 
+            b := shl(248, 0xff)
         } 
     } 
 } 
diff --git a/tests/e2e/detectors/test_data/incorrect-shift/0.7.6/shift_parameter_mixup.sol-0.7.6.zip b/tests/e2e/detectors/test_data/incorrect-shift/0.7.6/shift_parameter_mixup.sol-0.7.6.zip
Original file line number	Diff line number	Diff line change
		@@ -1,2 +1,2 @@
		C.f() (tests/e2e/detectors/test_data/incorrect-shift/0.7.6/shift_parameter_mixup.sol#3-7) contains an incorrect shift operation: a = 8 >> a (tests/e2e/detectors/test_data/incorrect-shift/0.7.6/shift_parameter_mixup.sol#5)
		C.f() (tests/e2e/detectors/test_data/incorrect-shift/0.7.6/shift_parameter_mixup.sol#3-8) contains an incorrect shift operation: a = 8 >> a (tests/e2e/detectors/test_data/incorrect-shift/0.7.6/shift_parameter_mixup.sol#5)