Threats Tagged 'cve-2025-40272'

A use-after-free race condition was identified and fixed in the Linux kernel's secret memory subsystem (memfd_secret). The flaw occurs when concurrent page faults on the same secret memory page cause improper ordering of freeing and remapping operations, potentially leading to supervisor not-present page faults. This vulnerability could impact confidentiality, integrity, and availability of the affected system. The issue has been resolved by correcting the order of operations in the fault handler to prevent the page from becoming prematurely available to the allocator.

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.