CVE-2024-49872 mm/gup: fix memfd_pin_folios alloc race panic

In the Linux kernel, the following vulnerability has been resolved: mm/gup: fix memfdpinfolios alloc race panic If memfdpinfolios tries to create a hugetlb page, but someone else already did, then folio gets the value -EEXIST here: folio = memfdallocfoliomemfd, startidx; if ISERRfolio ret =...