CVE-2022-50562

Vulnerability

Description

In the Linux kernel, the TPM (Trusted Platform Module) ACPI subsystem retrieves the event log area using the TPM2 or TCPA ACPI tables. The function acpi_get_table() is called to obtain the table, but the corresponding acpi_put_table() was missing, resulting in a memory leak [1][2]. This flaw exists in the tpm_read_log_acpi() function, where the ACPI memory is not released after use.

Exploitation

The memory leak occurs locally when the system accesses the TPM event log via ACPI. An attacker with local access could repeatedly trigger the vulnerable code path, causing gradual memory depletion. No special privileges beyond local user access are required, as the TPM event log reading is accessible to unprivileged processes in certain configurations.

Impact

Over time, the memory leak leads to exhaustion of system memory, potentially causing denial of service (DoS) by starving other processes of memory resources. The kernel may become unstable or crash under prolonged exploitation.

Mitigation

The fix is included in Linux kernel stable updates that apply commit 638cd298dfeb [1] and commit 8740a12ca2e2 [2]. Users should update their kernel to the latest stable version to mitigate this vulnerability. No workaround is available other than applying the patch.