CVE-2024-47676

In the Linux kernel, the following vulnerability has been resolved:

mm/hugetlb.c: fix UAF of vma in hugetlb fault pathway

Syzbot reports a UAF in hugetlb_fault(). This happens because vmf_anon_prepare() could drop the per-VMA lock and allow the current VMA to be freed before hugetlb_vma_unlock_read() is called.

We can fix this by using a modified version of vmf_anon_prepare() that doesn't release the VMA lock on failure, and then release it ourselves after hugetlb_vma_unlock_read().