CVE-2024-27022: fork: defer linking file vma until vma is fully initialized

Vulnerability summary

CVE-2024-27022 is a high (CVSS 7.8) Use of Uninitialized Resource vulnerability in linux. EPSS estimates a 0.27% chance of exploitation in the next 30 days, higher than 19.7% of scored vulnerabilities.

Timeline

1. 01-05-2024
   PublishedVulnerability first disclosed.
2. 30-10-2026
   Last modifiedVulnerability information updated.

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.

• CWE-908Use of Uninitialized ResourceThe product uses or accesses a resource that has not been initialized.