- Reported
-
- Issued
-
- Package
-
lucet-runtime
(crates.io)
- Type
-
Vulnerability
- Keywords
-
#use-after-free
- Aliases
-
- References
-
- CVSS Score
- 8.5
HIGH
- CVSS Details
-
- Attack Vector
- Network
- Attack Complexity
- High
- Privileges Required
- Low
- User Interaction
- None
- Scope
- Changed
- Confidentiality Impact
- High
- Integrity Impact
- High
- Availability Impact
- High
- CVSS Vector
- CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H
- Patched
-
no patched versions
Description
There is a bug in the main branch of Lucet's lucet-runtime
that allows a use-after-free in an Instance object that could
result in memory corruption, data race, or other related
issues. This bug was introduced early in the development
of Lucet and is present in all releases. As a result of
this bug, and dependent on the memory backing for the
Instance objects, it is possible to trigger a
use-after-free when the Instance is dropped.
Patches
Users should upgrade to the main branch of the Lucet
repository. Lucet does not provide versioned releases on
crates.io.
Workarounds
There is no way to remediate this vulnerability without
upgrading.
Description
Lucet uses a "pool" allocator for new WebAssembly
instances that are created. This pool allocator manages
everything from the linear memory of the wasm instance,
the runtime stack for async switching, as well as the
memory behind the Instance itself. Instances are referred
to via an InstanceHandle type which will, on drop,
release the memory backing the Instance back to the pool.
When an Instance is dropped, the fields of the Instance
are destructed top-to-bottom, however when the alloc:
Alloc field is destructed, the memory backing the
Instance is released back to the pool before the
destructors of the remaining fields are run. If another
thread allocates the same memory from the pool while
these destructors are still running, a race condition
occurs that can lead to use-after-free errors.
The bug was corrected by changing how the InstanceHandle
destructor operates to ensure that the memory backing an
Instance is only returned to the pool once the Instance
has been completely destroyed.
Advisory available under CC-BY-4.0
license.
Source: https://github.com/bytecodealliance/lucet/security/advisories/GHSA-hf79-8hjp-rrvq