CVE-2024-34704: era-compiler-solidity contains a `xor(zext(cmp), -1)` misoptimization

Vulnerability summary

CVE-2024-34704 is a medium (CVSS 5.9) Incorrect Calculation vulnerability in matter-labs era-compiler-solidity. EPSS estimates a 0.47% chance of exploitation in the next 30 days, higher than 40.4% of scored vulnerabilities.

Timeline

1. 13-05-2024
   PublishedVulnerability first disclosed.
2. 02-08-2024
   Last modifiedVulnerability information updated.

Description

era-compiler-solidity is the ZKsync compiler for Solidity. The problem occurred during instruction selection in the `DAGCombine` phase while visiting the XOR operation. The issue arises when attempting to fold the expression `!(x cc y)` into `(x !cc y)`. To perform this transformation, the second operand of XOR should be a constant representing the true value. However, it was incorrectly assumed that -1 represents the true value, when in fact, 1 is the correct representation, so this transformation for this case should be skipped. This vulnerability is fixed in 1.4.1.

• CWE-682Incorrect CalculationThe product performs a calculation that generates incorrect or unintended results that are later used in security-critical decisions or resource management.