CVE-2026-31597

Summary

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 Software

Weaknesses

References

• https://git.kernel.org/stable/c/36539c4d536f851a3b346a6ebb27b51bc3d77a94
• https://git.kernel.org/stable/c/35c2c05261d6f6d84aaa1355afa201d507943e76
• https://git.kernel.org/stable/c/3f5e74b5db9353b01ed50f4de84e75b755f8fbc2
• https://git.kernel.org/stable/c/6f072daefcab1d84ce37c073645615f63be91006
• https://git.kernel.org/stable/c/4cf2768a0291a0cdd0dae801ea0eafa3878a349d
• https://git.kernel.org/stable/c/d45ff441b416d4aa1af72b1db23d959601c04da2
• https://git.kernel.org/stable/c/76a602fdbb78dd05b2da06f74a988cebc97e82d0
• https://git.kernel.org/stable/c/925bf22c1b823e231b1baea761fe8a1512e442f2
• https://git.kernel.org/stable/c/7de554cabf160e331e4442e2a9ad874ca9875921

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