CVE-2025-40272

About vulnerability

In the Linux kernel, the following vulnerability has been resolved: mm/secretmem: fix use-after-free race in fault handler When a page fault occurs in a secret memory file created with memfd_secret(2), the kernel will allocate a new folio for it, mark the underlying page as not-present in the direct map, and add it to the file mapping. If two tasks cause a fault in the same page concurrently, both could end up allocating a folio and removing the page from the direct map, but only one would succeed in adding the folio to the file mapping. The task that failed undoes the effects of its attempt by (a) freeing the folio again and (b) putting the page back into the direct map. However, by doing these two operations in this order, the page becomes available to the allocator again before it is placed back in the direct mapping. If another task attempts to allocate the page between (a) and (b), and the kernel tries to access it via the direct map, it would result in a supervisor not-present page fault. Fix the ordering to restore the direct map before the folio is freed. A use-after-free race condition was found in the secretmem subsystem of the Linux kernel. When two tasks concurrently fault on the same page in a memfd_secret file, the losing task may free its folio before restoring the direct map entry. This allows the freed page to be reallocated while still unmapped, causing potential memory corruption.

Live-patch status from KernelCare for each operating system.