جزئیات آسیب‌پذیری

In the Linux kernel, the following vulnerability has been resolved: mm/util: don't read __page_2 for order-1 folios in snapshot_page() snapshot_page() currently reads __page_2 after checking nr_pages > 1, but it should only do so when nr_pages > 2. If an order-1 folio is allocated at the end of a vmemmap section, __page_2 will not exist and reading it will cause a fault. During DLPAR memory remove on a 22 TB ppc64le LPAR, snapshot_page() oopsed on the page isolation path while reading an order-1 folio's __page_2 from an adjacent absent section (unmapped vmemmap). Fix this to avoid reading memmap that doesn't exist (e.g., a vmemmap hole).

• https://git.kernel.org/stable/c/9668ffe0e2a5e2399dce281620198a2e415871fc
• https://git.kernel.org/stable/c/c649324571206a30949765320b91ccdb4c1722dc
• https://git.kernel.org/stable/c/7441d6348c70738e9ed307510db171c7a9b3f4bf