mm/huge_memory: drop beyond-EOF folios with the right number of refs

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: mm/huge_memory: drop beyond-EOF folios with the right number of refs When an after-split folio is large and needs to be dropped due to EOF, folio_put_refs(folio, folio_nr_pages(folio)) should be used to drop all page cache refs. Otherwise, the folio will not be freed, causing memory leak. This leak would happen on a filesystem with blocksize > page_size and a truncate is performed, where the blocksize makes folios split to >0 order ones, causing truncated folios not being freed.

References

• https://git.kernel.org/stable/c/86368616a9ce51f6b41efa251b6e066893851d67
• https://git.kernel.org/stable/c/92ad820a1f2d95d5a8d6c2bd3f391bbb068a5f9e
• https://git.kernel.org/stable/c/14efb4793519d73fb2902bb0ece319b886e4b4b9