CVE-2026-31597
Published: May 3, 2026Last modified: May 3, 2026
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.
Severity score breakdown
| Parameter | Value |
|---|---|
| Base score | 7.8 |
| Attack Vector | LOCAL |
| Attack complexity | LOW |
| Privileges required | LOW |
| User interaction | NONE |
| Scope | UNCHANGED |
| Confidentiality | HIGH |
| Integrity impact | HIGH |
| Availability impact | HIGH |
| Vector | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
Status
| Product | Release | Package | Status |
|---|---|---|---|
| Alpaquita Linux | 23 LTS | linux-lts | Vulnerable (6.1.170-r0) |
| 25 LTS | linux-lts | Fixed (6.12.85-r0) | |
| Stream | linux-lts | Fixed (6.12.85-r0) |
References
- https://git.kernel.org/stable/c/4cf2768a0291a0cdd0dae801ea0eafa3878a349d
- https://git.kernel.org/stable/c/6f072daefcab1d84ce37c073645615f63be91006
- https://git.kernel.org/stable/c/76a602fdbb78dd05b2da06f74a988cebc97e82d0
- https://git.kernel.org/stable/c/7de554cabf160e331e4442e2a9ad874ca9875921
- https://git.kernel.org/stable/c/925bf22c1b823e231b1baea761fe8a1512e442f2
- https://git.kernel.org/stable/c/d45ff441b416d4aa1af72b1db23d959601c04da2