ghsa-7f6x-jwh5-m9r4
Vulnerability from github
Impact
There was a bug in Wasmtime's code generator, Cranelift, for AArch64 targets where constant divisors could result in incorrect division results at runtime. The translation rules for constants did not take into account whether sign- or zero-extension should happen, which resulted in an incorrect value being placed into a register when a division was encountered. For example, a constant 32-bit unsigned divisor of 0xfffffffe would be incorrectly sign-extended to 64-bits to 0xfffffffffffffffe. Any kind of division of operands smaller than 64 bits is implemented with a 64-bit division instruction which would then result in an incorrect result because the divisor was larger than expected.
The impact of this bug is that programs executing within the WebAssembly sandbox would not behave according to the WebAssembly specification. This means that it is hypothetically possible for execution within the sandbox to go awry and WebAssembly programs could produce unexpected results. This should not impact hosts executing WebAssembly, but does affect the correctness of guest programs.
This bug was found with differential fuzzing of Wasmtime against other engines on the AArch64 platform. Fuzzing on AArch64 is not regularly performed at this time and the Wasmtime team is investigating how best to continuously fuzz AArch64 in the same manner as x86_64.
Patches
This bug has been patched and users should upgrade to Wasmtime version 0.38.2.
Workarounds
If upgrading is not an option at this time, direct users of Cranelift that control the exact Cranelift instructions being compiled can avoid the vulnerability by explicitly extending constant divisors to 64 bits using either the sextend.i64 or the uextend.i64 operation.
Note, though, that this issue only affects the AArch64 targets. Other platforms are not affected.
For more information
If you have any questions or comments about this advisory:
- Reach out to us on the Bytecode Alliance Zulip chat
- Open an issue in the bytecodealliance/wasmtime repository
{
"affected": [
{
"package": {
"ecosystem": "crates.io",
"name": "wasmtime"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "0.38.2"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"package": {
"ecosystem": "crates.io",
"name": "cranelift-codegen"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "0.85.2"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2022-31169"
],
"database_specific": {
"cwe_ids": [
"CWE-682"
],
"github_reviewed": true,
"github_reviewed_at": "2022-07-21T22:34:38Z",
"nvd_published_at": "2022-07-22T04:15:00Z",
"severity": "MODERATE"
},
"details": "### Impact\n\nThere was a bug in Wasmtime\u0027s code generator, Cranelift, for AArch64 targets where constant divisors could result in incorrect division results at runtime. The translation rules for constants did not take into account whether sign- or zero-extension should happen, which resulted in an incorrect value being placed into a register when a division was encountered. For example, a constant 32-bit unsigned divisor of `0xfffffffe` would be incorrectly sign-extended to 64-bits to `0xfffffffffffffffe`. Any kind of division of operands smaller than 64 bits is implemented with a 64-bit division instruction which would then result in an incorrect result because the divisor was larger than expected.\n\nThe impact of this bug is that programs executing within the WebAssembly sandbox would not behave according to the WebAssembly specification. This means that it is hypothetically possible for execution within the sandbox to go awry and WebAssembly programs could produce unexpected results. This should not impact hosts executing WebAssembly, but does affect the correctness of guest programs.\n\nThis bug was found with differential fuzzing of Wasmtime against other engines on the AArch64 platform. Fuzzing on AArch64 is not regularly performed at this time and the Wasmtime team is investigating how best to continuously fuzz AArch64 in the same manner as x86_64.\n\n### Patches\n\nThis bug has been patched and users should upgrade to Wasmtime version 0.38.2.\n\n### Workarounds\n\nIf upgrading is not an option at this time, direct users of Cranelift that control the exact Cranelift instructions being compiled can avoid the vulnerability by explicitly extending constant divisors to 64 bits using either the `sextend.i64` or the `uextend.i64` operation.\n\nNote, though, that this issue only affects the AArch64 targets. Other platforms are not affected.\n\n### For more information\n\nIf you have any questions or comments about this advisory:\n\n* Reach out to us on [the Bytecode Alliance Zulip chat](https://bytecodealliance.zulipchat.com/#narrow/stream/217126-wasmtime)\n* Open an issue in [the bytecodealliance/wasmtime repository](https://github.com/bytecodealliance/wasmtime/)",
"id": "GHSA-7f6x-jwh5-m9r4",
"modified": "2022-07-21T22:34:38Z",
"published": "2022-07-21T22:34:38Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-7f6x-jwh5-m9r4"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2022-31169"
},
{
"type": "WEB",
"url": "https://github.com/bytecodealliance/wasmtime/commit/2ba4bce5cc719e5a74e571a534424614e62ecc41"
},
{
"type": "PACKAGE",
"url": "https://github.com/bytecodealliance/wasmtime"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N",
"type": "CVSS_V3"
}
],
"summary": "Cranelift vulnerable to miscompilation of constant values in division on AArch64"
}
Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
- Confirmed: The vulnerability is confirmed from an analyst perspective.
- Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
- Patched: This vulnerability was successfully patched by the user reporting the sighting.
- Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
- Not confirmed: The user expresses doubt about the veracity of the vulnerability.
- Not patched: This vulnerability was not successfully patched by the user reporting the sighting.