CVE-2024-49858

/// Technical description

In the Linux kernel, the following vulnerability has been resolved:

efistub/tpm: Use ACPI reclaim memory for event log to avoid corruption

The TPM event log table is a Linux specific construct, where the data

produced by the GetEventLog() boot service is cached in memory, and

passed on to the OS using an EFI configuration table.

The use of EFI_LOADER_DATA here results in the region being left

unreserved in the E820 memory map constructed by the EFI stub, and this

is the memory description that is passed on to the incoming kernel by

kexec, which is therefore unaware that the region should be reserved.

Even though the utility of the TPM2 event log after a kexec is

questionable, any corruption might send the parsing code off into the

weeds and crash the kernel. So let's use EFI_ACPI_RECLAIM_MEMORY

instead, which is always treated as reserved by the E820 conversion

logic.

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References