CVE-2024-40917

/// Technical description

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

memblock: make memblock_set_node() also warn about use of MAX_NUMNODES

On an (old) x86 system with SRAT just covering space above 4Gb:

ACPI: SRAT: Node 0 PXM 0 [mem 0x100000000-0xfffffffff] hotplug

the commit referenced below leads to this NUMA configuration no longer

being refused by a CONFIG_NUMA=y kernel (previously

NUMA: nodes only cover 6144MB of your 8185MB e820 RAM. Not used.

No NUMA configuration found

Faking a node at [mem 0x0000000000000000-0x000000027fffffff]

was seen in the log directly after the message quoted above), because of

memblock_validate_numa_coverage() checking for NUMA_NO_NODE (only). This

in turn led to memblock_alloc_range_nid()'s warning about MAX_NUMNODES

triggering, followed by a NULL deref in memmap_init() when trying to

access node 64's (NODE_SHIFT=6) node data.

To compensate said change, make memblock_set_node() warn on and adjust

a passed in value of MAX_NUMNODES,

/// 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