CVE-2023-54309

Vulnerability

Overview

CVE-2023-54309 describes a race condition in the Linux kernel's TPM (Trusted Platform Module) vtpm proxy driver. The vulnerability arises because the /dev/vtpmx device is made visible to user space before the driver's workqueue is fully initialized. This ordering flaw can lead to memory corruption in the worst case, as operations on the device may trigger workqueue usage before the workqueue is ready.

Exploitation and

Attack Surface

An attacker with local access to the system could potentially exploit this race condition by opening /dev/vtpmx and triggering operations that rely on the uninitialized workqueue. The attack requires the ability to interact with the character device, which typically requires root privileges or membership in the appropriate group. The race window exists between device creation and workqueue initialization, making exploitation timing-dependent.

Impact

Successful exploitation could result in memory corruption, at minimum, a denial of service due to memory corruption, and in the worst case, arbitrary code execution in kernel context. The vulnerability affects systems using the TPM vtpm proxy driver, which is commonly used in virtualized environments to provide TPM functionality to guest VMs.

Mitigation

The fix, committed to the Linux kernel stable tree, addresses the issue by moving workqueue initialization to the very first step of the driver initialization process, ensuring the workqueue is ready before the device is exposed. Users should apply the relevant kernel updates from their distribution. No workqueue initialization is the first step of driver init [1][2][3].