Linux Kernel Vulnerability in Memory Handling by Vendor Linux

CVE-2025-39725

What is CVE-2025-39725?

A vulnerability exists in the Linux kernel concerning the handling of hwpoisoned large folios during memory reclamation. In the function shrink_folio_list(), if a hwpoisoned folio is large, it cannot be effectively managed by unmap_poisoned_folio(). This situation arises when there is a race between memory reclamation for large folios and memory_failure operations, potentially leading to a kernel panic. Specifically, without appropriate handling flags (TTU_SPLIT_HUGE_PMD), a null pointer dereference may occur. Even when the flags are applied, warnings may arise if the relevant page is not present in the swapcache. This issue remains rare in practical scenarios, but it highlights critical concerns within memory management processes in the kernel.

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