GHSA-g2xh-c426-v8mf
Vulnerability from github
Published
2023-09-04 16:39
Modified
2024-08-27 14:31
Severity ?
5.3 (Medium) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
Summary
Vyper: reversed order of side effects for some operations
Details

Impact

For the following (probably non-exhaustive) list of expressions, the compiler evaluates the arguments from right to left instead of left to right.

- unsafe_add - unsafe_sub - unsafe_mul - unsafe_div - pow_mod256 - |, &, ^ (bitwise operators) - bitwise_or (deprecated) - bitwise_and (deprecated) - bitwise_xor (deprecated) - raw_call - <, >, <=, >=, ==, != - in, not in (when lhs and rhs are enums)

This behaviour becomes a problem when the evaluation of one of the arguments produces side effects that other arguments depend on. The following expressions can produce side-effect:

  • state modifying external call
  • state modifying internal call
  • raw_call
  • pop() when used on a Dynamic Array stored in the storage
  • create_minimal_proxy_to
  • create_copy_of
  • create_from_blueprint

For example:

```Vyper f:uint256

@internal def side_effect() -> uint256: self.f = 12 return 1

@external def foo() -> uint256: return unsafe_add(self.f,self.side_effect()) # returns 13 instead of 1 ```

Vyper a:DynArray[uint256, 12] @external def bar() -> bool: self.a = [1,2,3] return len(self.a) == self.a.pop() # return false instead of true

Patches

not yet patched, will address in a future release. tracking in https://github.com/vyperlang/vyper/issues/3604.

Workarounds

When using expressions from the list above, make sure that the arguments of the expression do not produce side effects or, if one does, that no other argument is dependent on those side effects.

References

Are there any links users can visit to find out more?

Show details on source website

To clipboard 

{
  "affected": [
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "vyper"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "last_affected": "0.4.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2023-40015"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-670"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2023-09-04T16:39:00Z",
    "nvd_published_at": "2023-09-04T18:15:07Z",
    "severity": "MODERATE"
  },
  "details": "### Impact\n\nFor the following (probably non-exhaustive) list of expressions, the compiler evaluates the arguments from right to left instead of left to right.\n\n```\n- unsafe_add\n- unsafe_sub\n- unsafe_mul\n- unsafe_div\n- pow_mod256\n- |, \u0026, ^ (bitwise operators)\n- bitwise_or (deprecated)\n- bitwise_and (deprecated)\n- bitwise_xor (deprecated)\n- raw_call\n- \u003c, \u003e, \u003c=, \u003e=, ==, !=\n- in, not in (when lhs and rhs are enums)\n```\n\nThis behaviour becomes a problem when the evaluation of one of the arguments produces side effects that other arguments depend on. The following expressions can produce side-effect:\n\n- state modifying external call \n- state modifying internal call\n- `raw_call`\n- `pop()` when used on a Dynamic Array stored in the storage\n- `create_minimal_proxy_to`\n- `create_copy_of`\n- `create_from_blueprint`\n\nFor example:\n\n```Vyper\nf:uint256\n\n@internal\ndef side_effect() -\u003e uint256:\n    self.f = 12\n    return 1\n\n@external\ndef foo() -\u003e uint256:\n    return unsafe_add(self.f,self.side_effect()) # returns 13 instead of 1\n```\n\n```Vyper\na:DynArray[uint256, 12]\n@external\ndef bar() -\u003e bool:\n    self.a = [1,2,3]\n    return len(self.a) == self.a.pop() # return false instead of true\n```\n\n### Patches\nnot yet patched, will address in a future release. tracking in https://github.com/vyperlang/vyper/issues/3604.\n\n### Workarounds\n\nWhen using expressions from the list above, make sure that the arguments of the expression do not produce side effects or, if one does, that no other argument is dependent on those side effects.\n\n### References\n_Are there any links users can visit to find out more?_\n",
  "id": "GHSA-g2xh-c426-v8mf",
  "modified": "2024-08-27T14:31:49Z",
  "published": "2023-09-04T16:39:00Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/vyperlang/vyper/security/advisories/GHSA-g2xh-c426-v8mf"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2023-40015"
    },
    {
      "type": "WEB",
      "url": "https://github.com/vyperlang/vyper/issues/3604"
    },
    {
      "type": "WEB",
      "url": "https://github.com/pypa/advisory-database/tree/main/vulns/vyper/PYSEC-2023-167.yaml"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/vyperlang/vyper"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Vyper: reversed order of side effects for some operations"
}


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