CVE-2026-72212

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

mm/memory_hotplug: fix incorrect altmap passing in error path

In create_altmaps_and_memory_blocks(), when arch_add_memory() succeeds

with memmap_on_memory enabled, the vmemmap pages are allocated from

params.altmap. If create_memory_block_devices() subsequently fails, the

error path calls arch_remove_memory() with a NULL altmap instead of

params.altmap.

This is a bug that could lead to memory corruption. Since altmap is NULL,

vmemmap_free() falls back to freeing the vmemmap pages into the system

buddy allocator via free_pages() instead of the altmap.

arch_remove_memory() then immediately destroys the physical linear mapping

for this memory. This injects unowned pages into the buddy allocator,

causing machine checks or memory corruption if the system later attempts

to allocate and use those freed pages.

Fix this by passing params.altmap to arch_remove_memory() in the error

path.