CVE-2022-49760: 
Linux Kernel vulnerability analysis and mitigation

In the Linux kernel, a vulnerability was discovered in the mm/hugetlb component affecting the hugetlb_change_protection() function. The issue was related to incorrect handling of PTE markers in the context of userfaultfd write-protection (uffd-wp) operations. This vulnerability was assigned CVE-2022-49760 and was disclosed in March 2025 (NVD).

The vulnerability stems from two problematic cases in hugetlb_change_protection() when handling PTE markers: 1) When protecting an uffd-wp PTE marker a second time using uffd-wp, leading to corruption of the PTE marker in the '!huge_pte_none(pte)' case, and 2) When unprotecting a uffd-wp PTE marker, where a stale PTE value causes incorrect handling. These issues could result in treating corrupted PTE markers as present PTEs mapping invalid pages (NVD).

The vulnerability could be triggered through specific operations such as mapping a memfd backed by huge pages, registering uffd-wp, and performing certain operations like uffd-wp'ing an unmapped page multiple times or unregistering uffd-wp. When exploited, it could lead to system crashes through VM_BUG_ON assertions and potential memory corruption (NVD).

The vulnerability can be triggered through specific sequences of operations involving virtio-mem and background snapshots using uffd-wp on hugetlb in QEMU. A proof-of-concept exists that can trigger a VM_BUG_ON assertion (NVD).

The vulnerability has been resolved through patches in the Linux kernel. Two specific commits were created to address the issue: one fixing the immediate test case and another addressing potential issues with migration entries (NVD).