FKIE_CVE-2026-31597

Vulnerability from fkie_nvd - Published: 2026-04-24 15:16 - Updated: 2026-04-24 17:51
Severity ?
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.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/4cf2768a0291a0cdd0dae801ea0eafa3878a349d
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/76a602fdbb78dd05b2da06f74a988cebc97e82d0
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/925bf22c1b823e231b1baea761fe8a1512e442f2
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/d45ff441b416d4aa1af72b1db23d959601c04da2
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{
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nocfs2: fix use-after-free in ocfs2_fault() when VM_FAULT_RETRY\n\nfilemap_fault() may drop the mmap_lock before returning VM_FAULT_RETRY,\nas documented in mm/filemap.c:\n\n  \"If our return value has VM_FAULT_RETRY set, it\u0027s because the mmap_lock\n  may be dropped before doing I/O or by lock_folio_maybe_drop_mmap().\"\n\nWhen this happens, a concurrent munmap() can call remove_vma() and free\nthe vm_area_struct via RCU. The saved \u0027vma\u0027 pointer in ocfs2_fault() then\nbecomes a dangling pointer, and the subsequent trace_ocfs2_fault() call\ndereferences it -- a use-after-free.\n\nFix this by saving ip_blkno as a plain integer before calling\nfilemap_fault(), and removing vma from the trace event. Since\nip_blkno is copied by value before the lock can be dropped, it\nremains valid regardless of what happens to the vma or inode\nafterward."
    }
  ],
  "id": "CVE-2026-31597",
  "lastModified": "2026-04-24T17:51:40.810",
  "metrics": {},
  "published": "2026-04-24T15:16:37.457",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/4cf2768a0291a0cdd0dae801ea0eafa3878a349d"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/76a602fdbb78dd05b2da06f74a988cebc97e82d0"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/925bf22c1b823e231b1baea761fe8a1512e442f2"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/d45ff441b416d4aa1af72b1db23d959601c04da2"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Awaiting Analysis"
}


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