CVE-2024-27022: fork: defer linking file vma until vma is fully initialized
Description
In the Linux kernel, the following vulnerability has been resolved:
fork: defer linking file vma until vma is fully initialized
Thorvald reported a WARNING [1]. And the root cause is below race:
CPU 1 CPU 2
fork hugetlbfs_fallocate
dup_mmap hugetlbfs_punch_hole
i_mmap_lock_write(mapping);
vma_interval_tree_insert_after -- Child vma is visible through i_mmap tree.
i_mmap_unlock_write(mapping);
hugetlb_dup_vma_private -- Clear vma_lock outside i_mmap_rwsem!
i_mmap_lock_write(mapping);
hugetlb_vmdelete_list
vma_interval_tree_foreach
hugetlb_vma_trylock_write -- Vma_lock is cleared.
tmp->vm_ops->open -- Alloc new vma_lock outside i_mmap_rwsem!
hugetlb_vma_unlock_write -- Vma_lock is assigned!!!
i_mmap_unlock_write(mapping);
hugetlb_dup_vma_private() and hugetlb_vm_op_open() are called outside
i_mmap_rwsem lock while vma lock can be used in the same time. Fix this
by deferring linking file vma until vma is fully initialized. Those vmas
should be initialized first before they can be used.
Classification
CVE ID: CVE-2024-27022
Affected Products
Vendor: Linux
Product: Linux
Exploit Prediction Scoring System (EPSS)
EPSS Score: 0.04% (probability of being exploited)
EPSS Percentile: 11.72% (scored less or equal to compared to others)
EPSS Date: 2025-02-21 (when was this score calculated)
References
https://git.kernel.org/stable/c/abdb88dd272bbeb93efe01d8e0b7b17e24af3a34https://git.kernel.org/stable/c/35e351780fa9d8240dd6f7e4f245f9ea37e96c19