CVE-2022-39394: Out of bounds write in `wasmtime_trap_code` C API function

Impact

There is a bug in Wasmtime’s C API implementation where the definition of the wasmtime_trap_code does not match its declared signature in the wasmtime/trap.h header file. This discrepancy causes the function implementation to perform a 4-byte write into a 1-byte buffer provided by the caller. This can lead to three zero bytes being written beyond the 1-byte location provided by the caller.

Patches

This bug has been patched and users should upgrade to Wasmtime 2.0.2.

Workarounds

This can be worked around by providing a 4-byte buffer casted to a 1-byte buffer when calling wasmtime_trap_code. Users of the wasmtime crate are not affected by this issue, only users of the C API function wasmtime_trap_code are affected.

References

• Definition of wasmtime_trap_code
• Mailing list announcement
• Patch to fix for main branch

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