SHA3_64 Vulnerability in compile_ir.py

Severity

High Risk

Summary

There is an error in the calculation of SHA3_64, which will produce wrong hash results and may affect the access of HashMap objects.

Vulnerability Details

line 583 in compile_ir.py

# SHA3 a 64 byte value
elif code.value == "sha3_64":
	o = _compile_to_assembly(code.args[0], withargs, existing_labels, break_dest, height)
	o.extend(_compile_to_assembly(code.args[1], withargs, existing_labels, break_dest, height))
	o.extend(
		[
			*PUSH(MemoryPositions.FREE_VAR_SPACE2),
			"MSTORE",
			*PUSH(MemoryPositions.FREE_VAR_SPACE),
			"MSTORE",
			*PUSH(64),
			*PUSH(MemoryPositions.FREE_VAR_SPACE),
			"SHA3",
		]
	)
	return o

o.extend(_compile_to_assembly(code.args[1], withargs, existing_labels, break_dest, height)) should be on height+1. This code will affect the correct access of the withargs variable.

Impact

Because SHA3_64 is related to the reading and writing of HashMap objects, it has an important impact on the data on the contract chain. The overall impact should be high level.

POC Code:

(with _loc
	(with val 1 
		(with key 2 
			(sha3_64 val key))) 
				(seq 
					(sstore _loc 
					(with x (sload _loc) 
						(with ans (add x 1) (seq (assert (ge ans x)) ans))))))

python -m vyper --vyper-ir bug.ir

the generated bytecode: 6001600281806020525f5260405f2090509050805460018101818110610026579050815550005b5f80fd

0000    60  PUSH1 0x01
0002    60  PUSH1 0x02
0004    81  DUP2
0005    80  DUP1       *********** bad code here!!!!!!
0006    60  PUSH1 0x20
0008    52  MSTORE