CVE-2026-31597

About vulnerability

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.

Affected product:

AlmaLinux 9.2 ESU , Amazon Linux 2 ELS , CentOS 7 ELS , CentOS 8.4 ELS , CentOS 8.5 ELS , CentOS Stream 8 ELS , CloudLinux 7 ELS , Debian 10 ELS , Oracle Linux 7 ELS , RHEL 7 ELS , TuxCare 9.6 ESU , Ubuntu 16.04 ELS , Ubuntu 18.04 ELS , Ubuntu 20.04 ELS

Affected packages:

linux @ 4.15.0 (+16 more)

Live-patch status from KernelCare for each operating system.