CVE-2024-40917: memblock: make memblock_set_node() also warn about use of MAX_NUMNODES

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2024-07-12 · updated 2026-06-17

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, just like various other functions already do.

Affected products

Linux kernel: from 6.6.70 before 6.6.72; from 6.8 before 6.9.6; 6.10-rc1, 6.10-rc2, 6.10-rc3 — fixed in 6.6.72, 6.9.6

How to fix

Upgrade to a fixed version: Linux kernel 6.6.72, 6.9.6. Check the vendor advisory for mitigations.

References

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