CVE-2026-31597

/// Technical description

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

ocfs2: fix use-after-free in ocfs2_fault() when VM_FAULT_RETRY

filemap_fault() may drop the mmap_lock before returning VM_FAULT_RETRY,

as documented in mm/filemap.c:

"If our return value has VM_FAULT_RETRY set, it's because the mmap_lock

may be dropped before doing I/O or by lock_folio_maybe_drop_mmap()."

When this happens, a concurrent munmap() can call remove_vma() and free

the vm_area_struct via RCU. The saved 'vma' pointer in ocfs2_fault() then

becomes a dangling pointer, and the subsequent trace_ocfs2_fault() call

dereferences it -- a use-after-free.

Fix this by saving ip_blkno as a plain integer before calling

filemap_fault(), and removing vma from the trace event. Since

ip_blkno is copied by value before the lock can be dropped, it

remains valid regardless of what happens to the vma or inode

afterward.

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References