rustsec-2022-0076
Vulnerability from osv_rustsec
Published
2022-11-10 12:00
Modified
2023-03-15 23:49
Summary
Bug in Wasmtime implementation of pooling instance allocator
Details

Bug in Wasmtime's implementation of its pooling instance allocator when the allocator is configured to give WebAssembly instances a maximum of zero pages of memory.

In this configuration, the virtual memory mapping for WebAssembly memories did not meet the compiler-required configuration requirements for safely executing WebAssembly modules. Wasmtime's default settings require virtual memory page faults to indicate that wasm reads/writes are out-of-bounds, but the pooling allocator's configuration would not create an appropriate virtual memory mapping for this meaning out of bounds reads/writes can successfully read/write memory unrelated to the wasm sandbox within range of the base address of the memory mapping created by the pooling allocator.

This bug is not applicable with the default settings of the wasmtime crate.

This bug can only be triggered by setting InstanceLimits::memory_pages to zero.

This is expected to be a very rare configuration since this means that wasm modules cannot allocate any pages of linear memory.

All wasm modules produced by all current toolchains are highly likely to use linear memory, so it's expected to be unlikely that this configuration is set to zero by any production embedding of Wasmtime.

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{
  "affected": [
    {
      "database_specific": {
        "categories": [
          "memory-corruption",
          "memory-exposure"
        ],
        "cvss": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N",
        "informational": null
      },
      "ecosystem_specific": {
        "affected_functions": null,
        "affects": {
          "arch": [],
          "functions": [
            "wasmtime::Config::allocation_strategy",
            "wasmtime::PoolingAllocationConfig::instance_memory_pages"
          ],
          "os": []
        }
      },
      "package": {
        "ecosystem": "crates.io",
        "name": "wasmtime",
        "purl": "pkg:cargo/wasmtime"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0.0.0-0"
            },
            {
              "fixed": "1.0.2"
            },
            {
              "introduced": "2.0.0"
            },
            {
              "fixed": "2.0.2"
            }
          ],
          "type": "SEMVER"
        }
      ],
      "versions": []
    }
  ],
  "aliases": [
    "CVE-2022-39392",
    "GHSA-44mr-8vmm-wjhg"
  ],
  "database_specific": {
    "license": "CC0-1.0"
  },
  "details": "Bug in Wasmtime\u0027s implementation of its pooling instance allocator when the allocator is configured to give WebAssembly instances a maximum of zero pages of memory.\n\nIn this configuration, the virtual memory mapping for WebAssembly memories did not meet the compiler-required configuration requirements for safely executing WebAssembly modules. Wasmtime\u0027s default settings require virtual memory page faults to indicate that wasm reads/writes are out-of-bounds, but the pooling allocator\u0027s configuration would not create an appropriate virtual memory mapping for this meaning out of bounds reads/writes can successfully read/write memory unrelated to the wasm sandbox within range of the base address of the memory mapping created by the pooling allocator.\n\nThis bug is not applicable with the default settings of the `wasmtime` crate.\n\nThis bug can only be triggered by setting `InstanceLimits::memory_pages` to zero.\n\nThis is expected to be a very rare configuration since this means that wasm modules cannot allocate any pages of linear memory.\n\nAll wasm modules produced by all current toolchains are highly likely to use linear memory, so it\u0027s expected to be unlikely that this configuration is set to zero by any production embedding of Wasmtime.",
  "id": "RUSTSEC-2022-0076",
  "modified": "2023-03-15T23:49:40Z",
  "published": "2022-11-10T12:00:00Z",
  "references": [
    {
      "type": "PACKAGE",
      "url": "https://crates.io/crates/wasmtime"
    },
    {
      "type": "ADVISORY",
      "url": "https://rustsec.org/advisories/RUSTSEC-2022-0076.html"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-44mr-8vmm-wjhg"
    },
    {
      "type": "WEB",
      "url": "https://github.com/bytecodealliance/wasmtime/commit/e60c3742904ccbb3e26da201c9221c38a4981d72"
    }
  ],
  "related": [],
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Bug in Wasmtime implementation of pooling instance allocator"
}


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