CVE-2025-39910

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

mm/vmalloc, mm/kasan: respect gfp mask in kasan_populate_vmalloc()

kasan_populate_vmalloc() and its helpers ignore the caller's gfp_mask and

always allocate memory using the hardcoded GFP_KERNEL flag. This makes

them inconsistent with vmalloc(), which was recently extended to support

GFP_NOFS and GFP_NOIO allocations.

Page table allocations performed during shadow population also ignore the

external gfp_mask. To preserve the intended semantics of GFP_NOFS and

GFP_NOIO, wrap the apply_to_page_range() calls into the appropriate

memalloc scope.

xfs calls vmalloc with GFP_NOFS, so this bug could lead to deadlock.

There was a report here

https://lkml.kernel.org/r/[email protected]

This patch:

- Extends kasan_populate_vmalloc() and helpers to take gfp_mask;

- Passes gfp_mask down to alloc_pages_bulk() and __get_free_page();

- Enforces GFP_NOFS/NOIO semantics with memalloc_*_save()/restore()

around apply_to_page_range();

- Updates vmalloc.c and percpu allocator call sites accordingly.