CVE-2024-56617

/// Technical description

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

cacheinfo: Allocate memory during CPU hotplug if not done from the primary CPU

Commit

5944ce092b97 ("arch_topology: Build cacheinfo from primary CPU")

adds functionality that architectures can use to optionally allocate and

build cacheinfo early during boot. Commit

6539cffa9495 ("cacheinfo: Add arch specific early level initializer")

lets secondary CPUs correct (and reallocate memory) cacheinfo data if

needed.

If the early build functionality is not used and cacheinfo does not need

correction, memory for cacheinfo is never allocated. x86 does not use

the early build functionality. Consequently, during the cacheinfo CPU

hotplug callback, last_level_cache_is_valid() attempts to dereference

a NULL pointer:

BUG: kernel NULL pointer dereference, address: 0000000000000100

#PF: supervisor read access in kernel mode

#PF: error_code(0x0000) - not present page

PGD 0 P4D 0

Oops: 0000 [#1] PREEPMT SMP NOPTI

/// 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