In the Linux kernel, the following vulnerability has been resolved:
mm/mm_init: handle alloc_percpu failure in free_area_init_core_hotplug
We miss a failed allocation check for pgdat->per_cpu_nodestats, which
results in a NULL deref when we offset into the per-cpu area.
Propagate -ENOMEM up the stack and leave per_cpu_nodestats pointing
at boot_nodestats so a later online can retry the allocation.
hotadd_init_pgdat() returns NULL on failure, which __try_online_node()
already maps to -ENOMEM.
On failure nothing needs to be unwound:
– the node is never marked online
– per_cpu_nodestats is left pointing at boot_nodestats
– __add_memory_resource() cleans up pending memblock resources
– later online attempts retry the per_cpu_nodestats allocation
