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.

KASAN’s vmalloc shadow population ignored the caller’s gfp_mask, allocating with GFP_KERNEL even in GFP_NOFS/NOIO contexts. This could trigger filesystem/block reclaim and re-entrancy, leading to deadlocks under load (e.g., XFS calling vmalloc(GFP_NOFS)).

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.