CVE-2026-31597

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.

Predictions

Heuristic predictions, AS-IS, for prioritization only.

Mitigations

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
• https://www.suse.com/security/cve/CVE-2026-31597.html
• https://security-tracker.debian.org/tracker/CVE-2026-31597

CWEs

CWE-416