ghsa-gwc9-348x-qwv2
Vulnerability from github
There is a use after free vulnerability in Wasmtime when both running Wasm that uses externref
s and enabling epoch interruption in Wasmtime. If you are not explicitly enabling epoch interruption (it is disabled by default) then you are not affected. If you are explicitly disabling the Wasm reference types proposal (it is enabled by default) then you are also not affected.
The use after free is caused by Cranelift failing to emit stack maps when there are safepoints inside cold blocks. Cold blocks occur when epoch interruption is enabled. Cold blocks are emitted at the end of compiled functions, and change the order blocks are emitted versus defined. This reordering accidentally caused Cranelift to skip emitting some stack maps because it expected to emit the stack maps in block definition order, rather than block emission order. When Wasmtime would eventually collect garbage, it would fail to find live references on the stack because of the missing stack maps, think that they were unreferenced garbage, and therefore reclaim them. Then after the collection ended, the Wasm code could use the reclaimed-too-early references, which is a use after free.
This bug was discovered while extending our fuzz targets for externref
s and GC in Wasmtime. The updated fuzz target thoroughly exercises these code paths and feature combinations now. We have also added a regression test for this bug. Released versions 0.34.2 and 0.35.2, which fix the vulnerability. We recommend all Wasmtime users upgrade to these patched versions. If upgrading is not an option for you at this time, you can avoid the vulnerability by either disabling the Wasm reference types proposal or by disabling epoch interruption if you were previously enabling it.
{ "affected": [ { "package": { "ecosystem": "crates.io", "name": "wasmtime" }, "ranges": [ { "events": [ { "introduced": "0" }, { "fixed": "0.34.2" } ], "type": "ECOSYSTEM" } ] }, { "package": { "ecosystem": "crates.io", "name": "wasmtime" }, "ranges": [ { "events": [ { "introduced": "0.35.0" }, { "fixed": "0.35.2" } ], "type": "ECOSYSTEM" } ] } ], "aliases": [ "CVE-2022-24791" ], "database_specific": { "cwe_ids": [ "CWE-416" ], "github_reviewed": true, "github_reviewed_at": "2022-04-01T13:36:12Z", "nvd_published_at": "2022-03-31T23:15:00Z", "severity": "HIGH" }, "details": "There is a use after free vulnerability in Wasmtime when both running Wasm that uses `externref`s and enabling [epoch interruption](https://docs.rs/wasmtime/latest/wasmtime/struct.Config.html#method.epoch_interruption) in Wasmtime. If you are not explicitly enabling epoch interruption (it is disabled by default) then you are not affected. If you are explicitly disabling the Wasm reference types proposal (it is enabled by default) then you are also not affected.\n\nThe use after free is caused by Cranelift failing to emit stack maps when there are safepoints inside cold blocks. Cold blocks occur when epoch interruption is enabled. Cold blocks are emitted at the end of compiled functions, and change the order blocks are emitted versus defined. This reordering accidentally caused Cranelift to skip emitting some stack maps because it expected to emit the stack maps in block definition order, rather than block emission order. When Wasmtime would eventually collect garbage, it would fail to find live references on the stack because of the missing stack maps, think that they were unreferenced garbage, and therefore reclaim them. Then after the collection ended, the Wasm code could use the reclaimed-too-early references, which is a use after free.\n\nThis bug was discovered while extending our fuzz targets for `externref`s and GC in Wasmtime. The updated fuzz target thoroughly exercises these code paths and feature combinations now. We have also added a regression test for this bug. Released versions 0.34.2 and 0.35.2, which fix the vulnerability. We recommend all Wasmtime users upgrade to these patched versions. If upgrading is not an option for you at this time, you can avoid the vulnerability by either disabling the Wasm reference types proposal or by disabling epoch interruption if you were previously enabling it.", "id": "GHSA-gwc9-348x-qwv2", "modified": "2022-04-12T23:16:15Z", "published": "2022-04-01T13:36:12Z", "references": [ { "type": "WEB", "url": "https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-gwc9-348x-qwv2" }, { "type": "ADVISORY", "url": "https://nvd.nist.gov/vuln/detail/CVE-2022-24791" }, { "type": "WEB", "url": "https://github.com/bytecodealliance/wasmtime/commit/666c2554ea0e1728c35aa41178cf235920db888a" }, { "type": "WEB", "url": "https://docs.rs/wasmtime/latest/wasmtime/struct.Config.html#method.epoch_interruption" }, { "type": "WEB", "url": "https://github.com/WebAssembly/reference-types" }, { "type": "PACKAGE", "url": "https://github.com/bytecodealliance/wasmtime" }, { "type": "WEB", "url": "https://rustsec.org/advisories/RUSTSEC-2022-0016.html" } ], "schema_version": "1.4.0", "severity": [ { "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H", "type": "CVSS_V3" } ], "summary": "Use after free in Wasmtime" }
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.