CVE-2024-45022 Information

Description

In the Linux kernel the following vulnerability has been resolved:

mm/vmalloc: fix page mapping if vm_area_alloc_pages() with high order fallback to order 0

The __vmap_pages_range_noflush() assumes its argument pages contains pages with the same page shift. However since commit e9c3cda4d86e (\mm vmalloc: fix high order __GFP_NOFAIL allocations) if gfp_flags includes __GFP_NOFAIL with high order in vm_area_alloc_pages() and page allocation failed for high order the pages may contain two different page shifts (high order and order-0). This could lead __vmap_pages_range_noflush() to perform incorrect mappings potentially resulting in memory corruption.

Users might encounter this as follows (vmap_allow_huge = true 2M is for PMD_SIZE):

kvmalloc(2M __GFP_NOFAIL|GFP_X) __vmalloc_node_range_noprof(vm_flags=VM_ALLOW_HUGE_VMAP) vm_area_alloc_pages(order=9) —> order-9 allocation failed and fallback to order-0 vmap_pages_range() vmap_pages_range_noflush() __vmap_pages_range_noflush(page_shift = 21) —-> wrong mapping happens

We can remove the fallback code because if a high-order allocation fails __vmalloc_node_range_noprof() will retry with order-0. Therefore it is unnecessary to fallback to order-0 here. Therefore fix this by removing the fallback code.

Reference

https://git.kernel.org/stable/c/fd1ffbb50ef4da5e1378a46616b6d7407dc795da https://git.kernel.org/stable/c/de7bad86345c43cd040ed43e20d9fad78a3ee59f https://git.kernel.org/stable/c/c91618816f4d21fc574d7577a37722adcd4075b2 https://git.kernel.org/stable/c/61ebe5a747da649057c37be1c37eb934b4af79ca