{
  "affected": [
    {
      "ranges": [
        {
          "events": [
            {
              "introduced": "4c8ff7095bef64fc47e996a938f7d57f9e077da3"
            },
            {
              "fixed": "57bc678f36ac03281e877c6b84877b43f964143f"
            },
            {
              "fixed": "ef57cd3329b40c739b9a2e1a8a21ecc4171c6280"
            },
            {
              "fixed": "f5154cf3ce1c8193f0c1891d3769f62740cfe6fe"
            },
            {
              "fixed": "c76cf339b87975ae5b2c06d2d774d5667d25a12a"
            },
            {
              "fixed": "2c97dcb6147c8f7f25c629b93be1e69617de5d4a"
            },
            {
              "fixed": "39d4ee19c1e7d753dd655aebee632271b171f43a"
            }
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "type": "GIT"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Linux",
        "name": "Kernel"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "5.6.0"
            },
            {
              "fixed": "6.1.175"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.2.0"
            },
            {
              "fixed": "6.6.136"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.7.0"
            },
            {
              "fixed": "6.12.84"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.13.0"
            },
            {
              "fixed": "6.18.25"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.19.0"
            },
            {
              "fixed": "7.0.2"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "database_specific": {
    "cna_assigner": "Linux",
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/31xxx/CVE-2026-31702.json"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nf2fs: fix use-after-free of sbi in f2fs_compress_write_end_io()\n\nIn f2fs_compress_write_end_io(), dec_page_count(sbi, type) can bring\nthe F2FS_WB_CP_DATA counter to zero, unblocking\nf2fs_wait_on_all_pages() in f2fs_put_super() on a concurrent unmount\nCPU. The unmount path then proceeds to call\nf2fs_destroy_page_array_cache(sbi), which destroys\nsbi-\u003epage_array_slab via kmem_cache_destroy(), and eventually\nkfree(sbi). Meanwhile, the bio completion callback is still executing:\nwhen it reaches page_array_free(sbi, ...), it dereferences\nsbi-\u003epage_array_slab — a destroyed slab cache — to call\nkmem_cache_free(), causing a use-after-free.\n\nThis is the same class of bug as CVE-2026-23234 (which fixed the\nequivalent race in f2fs_write_end_io() in data.c), but in the\ncompressed writeback completion path that was not covered by that fix.\n\nFix this by moving dec_page_count() to after page_array_free(), so\nthat all sbi accesses complete before the counter decrement that can\nunblock unmount. For non-last folios (where atomic_dec_return on\ncic-\u003epending_pages is nonzero), dec_page_count is called immediately\nbefore returning — page_array_free is not reached on this path, so\nthere is no post-decrement sbi access. For the last folio,\npage_array_free runs while the F2FS_WB_CP_DATA counter is still\nnonzero (this folio has not yet decremented it), keeping sbi alive,\nand dec_page_count runs as the final operation.",
  "id": "CVE-2026-31702",
  "modified": "2026-07-08T05:39:10.957049059Z",
  "published": "2026-05-01T13:56:01.601Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/2c97dcb6147c8f7f25c629b93be1e69617de5d4a"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/39d4ee19c1e7d753dd655aebee632271b171f43a"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/57bc678f36ac03281e877c6b84877b43f964143f"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/c76cf339b87975ae5b2c06d2d774d5667d25a12a"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/ef57cd3329b40c739b9a2e1a8a21ecc4171c6280"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/f5154cf3ce1c8193f0c1891d3769f62740cfe6fe"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/31xxx/CVE-2026-31702.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-31702"
    },
    {
      "type": "PACKAGE",
      "url": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
    }
  ],
  "schema_version": "1.7.5",
  "summary": "f2fs: fix use-after-free of sbi in f2fs_compress_write_end_io()"
}