Wasmtime is a standalone runtime for WebAssembly. Prior to version 2.0.2, there is a bug in Wasmtimes 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. Wasmtimes default settings require virtual memory page faults to indicate that wasm reads/writes are out-of-bounds, but the pooling allocators 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 its expected to be unlikely that this configuration is set to zero by any production embedding of Wasmtime. This bug has been patched and users should upgrade to Wasmtime 2.0.2. This bug can be worked around by increasing the memory_pages
allotment when configuring the pooling allocator to a value greater than zero. If an embedding wishes to still prevent memory from actually being used then the Store::limiter
method can be used to dynamically disallow growth of memory beyond 0 bytes large. Note that the default memory_pages
value is greater than zero.
The product reads data past the end, or before the beginning, of the intended buffer.
Name | Vendor | Start Version | End Version |
---|---|---|---|
Wasmtime | Bytecodealliance | * | 1.0.2 (excluding) |
Wasmtime | Bytecodealliance | 2.0.0 (including) | 2.0.2 (excluding) |
Firefox | Ubuntu | bionic | * |
Firefox | Ubuntu | focal | * |
Firefox | Ubuntu | trusty | * |
Firefox | Ubuntu | xenial | * |
Mozjs38 | Ubuntu | bionic | * |
Mozjs38 | Ubuntu | esm-apps/bionic | * |
Mozjs38 | Ubuntu | upstream | * |
Mozjs52 | Ubuntu | bionic | * |
Mozjs52 | Ubuntu | esm-apps/focal | * |
Mozjs52 | Ubuntu | esm-infra/bionic | * |
Mozjs52 | Ubuntu | focal | * |
Mozjs52 | Ubuntu | upstream | * |
Mozjs68 | Ubuntu | focal | * |
Mozjs68 | Ubuntu | upstream | * |
Mozjs78 | Ubuntu | esm-apps/jammy | * |
Mozjs78 | Ubuntu | jammy | * |
Mozjs78 | Ubuntu | kinetic | * |
Mozjs78 | Ubuntu | lunar | * |
Mozjs78 | Ubuntu | upstream | * |
Mozjs91 | Ubuntu | jammy | * |
Mozjs91 | Ubuntu | upstream | * |
Thunderbird | Ubuntu | bionic | * |
Thunderbird | Ubuntu | devel | * |
Thunderbird | Ubuntu | focal | * |
Thunderbird | Ubuntu | jammy | * |
Thunderbird | Ubuntu | kinetic | * |
Thunderbird | Ubuntu | lunar | * |
Thunderbird | Ubuntu | mantic | * |
Thunderbird | Ubuntu | noble | * |
Thunderbird | Ubuntu | trusty | * |
Thunderbird | Ubuntu | xenial | * |