NFS: Fix nfs_netfs_issue_read() xarray locking for writeback interrupt

{
  "id": "85c5fd353a8ed1a3f538f3da68d0ec71f0a80e5bd59b4d90844a55c63f4f6008",
  "url": "https://osv.dev/vulnerability/CVE-2024-27031",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "NFS: Fix nfs_netfs_issue_read() xarray locking for writeback interrupt",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: NFS: Fix nfs_netfs_issue_read() xarray locking for writeback interrupt The loop inside nfs_netfs_issue_read() currently does not disable interrupts while iterating through pages in the xarray to submit for NFS read. This is not safe though since after taking xa_lock, another page in the mapping could be processed for writeback inside an interrupt, and deadlock can occur. The fix is simple and clean if we use xa_for_each_range(), which handles the iteration with RCU while reducing code complexity. The problem is easily reproduced with the following test: mount -o vers=3,fsc 127.0.0.1:/export /mnt/nfs dd if=/dev/zero of=/mnt/nfs/file1.bin bs=4096 count=1 echo 3 > /proc/sys/vm/drop_caches dd if=/mnt/nfs/file1.bin of=/dev/null umount /mnt/nfs On the console with a lockdep-enabled kernel a message similar to the following will be seen: ================================ WARNING: inconsistent lock state 6.7.0-lockdbg+ #10 Not tainted -------------------------------- inconsistent {IN-SOFTIRQ-W} -> {SOFTIRQ-ON-W} usage. test5/1708 [HC0[0]:SC0[0]:HE1:SE1] takes: ffff888127baa598 (&xa->xa_lock#4){+.?.}-{3:3}, at: nfs_netfs_issue_read+0x1b2/0x4b0 [nfs] {IN-SOFTIRQ-W} state was registered at: lock_acquire+0x144/0x380 _raw_spin_lock_irqsave+0x4e/0xa0 __folio_end_writeback+0x17e/0x5c0 folio_end_writeback+0x93/0x1b0 iomap_finish_ioend+0xeb/0x6a0 blk_update_request+0x204/0x7f0 blk_mq_end_request+0x30/0x1c0 blk_complete_reqs+0x",
    "evidence": "osv:CVE-2024-27031",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "6.6.23",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.7.11",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.8.2",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "CVE-2024-27031",
      "aliases": [
        "CVE-2024-27031"
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
                {
                  "introduced": "000dbe0bec058cbf2ca9e156e4a5584f5158b0f9"
                },
                {
                  "fixed": "ad27382f8495f8ef6d2c66c413d756bfd13c0598"
                },
                {
                  "fixed": "8df1678c021ffeb20ef8a203bd9413f3ed9b0e9a"
                },
                {
                  "fixed": "8a2e5977cecd3cde6a0e3e86b7b914d00240e5dc"
                },
                {
                  "fixed": "fd5860ab6341506004219b080aea40213b299d2e"
                }
              ]
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2024-27031.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.4.0"
                },
                {
                  "fixed": "6.6.23"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.7.0"
                },
                {
                  "fixed": "6.7.11"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.8.0"
                },
                {
                  "fixed": "6.8.2"
                }
              ]
            }
          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2024-27031.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:30.328802878Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/8a2e5977cecd3cde6a0e3e86b7b914d00240e5dc",
        "https://git.kernel.org/stable/c/8df1678c021ffeb20ef8a203bd9413f3ed9b0e9a",
        "https://git.kernel.org/stable/c/ad27382f8495f8ef6d2c66c413d756bfd13c0598",
        "https://git.kernel.org/stable/c/fd5860ab6341506004219b080aea40213b299d2e",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2024/27xxx/CVE-2024-27031.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2024-27031",
        "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
      ],
      "provider_metadata": {
        "cna_assigner": "Linux",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2024/27xxx/CVE-2024-27031.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2024-27031",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 496935,
  "published_at": "2024-05-01T12:53:29.362+00:00"
}