CVE-2024-49964: 
Linux Kernel vulnerability analysis and mitigation

A vulnerability in the Linux kernel's memory management subsystem (CVE-2024-49964) was discovered affecting versions from 6.11 up to (excluding) 6.11.3. The issue involves a memory leak in the hugetlb subsystem where memfdpinfolios followed by unpinfolios fails to properly restore freehuge_pages when pages were not already faulted in (Kernel Patch).

The vulnerability stems from incorrect reference counting in the memfdpinfolios function. The issue occurs because the folio refcount for pages created by memfdallocfolio never reaches 0 due to multiple reference count additions: one from foliorefunfreeze(folio, 1), another from foliotryget(), and 512 from hugetlbaddtopagecache() on x86 systems. The CVSS v3.1 base score is 5.5 (Medium) with vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H (NVD).

The vulnerability results in a memory leak in the Linux kernel's huge pages management system. When memfdpinfolios is followed by unpinfolios operations, it fails to properly restore freehuge_pages if the pages were not already faulted in, potentially leading to resource exhaustion (Kernel Patch).

The issue has been fixed in Linux kernel version 6.11.3. The patch adds an additional folio_put call when h (hstate) is present to properly handle the reference counting. System administrators should upgrade affected systems to the patched version (Kernel Patch).