nfsd: make sure exp active before svc_export_show

{
  "id": "47ad38c4a5caa8536d267688a83a0f2381c94738ef06abad156518e0164fcb03",
  "url": "https://osv.dev/vulnerability/CVE-2024-56558",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "nfsd: make sure exp active before svc_export_show",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: nfsd: make sure exp active before svc_export_show The function `e_show` was called with protection from RCU. This only ensures that `exp` will not be freed. Therefore, the reference count for `exp` can drop to zero, which will trigger a refcount use-after-free warning when `exp_get` is called. To resolve this issue, use `cache_get_rcu` to ensure that `exp` remains active. ------------[ cut here ]------------ refcount_t: addition on 0; use-after-free. WARNING: CPU: 3 PID: 819 at lib/refcount.c:25 refcount_warn_saturate+0xb1/0x120 CPU: 3 UID: 0 PID: 819 Comm: cat Not tainted 6.12.0-rc3+ #1 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.1-2.fc37 04/01/2014 RIP: 0010:refcount_warn_saturate+0xb1/0x120 ... Call Trace: e_show+0x20b/0x230 [nfsd] seq_read_iter+0x589/0x770 seq_read+0x1e5/0x270 vfs_read+0x125/0x530 ksys_read+0xc1/0x160 do_syscall_64+0x5f/0x170 entry_SYSCALL_64_after_hwframe+0x76/0x7e",
    "evidence": "osv:CVE-2024-56558",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "5.4.287",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "5.10.231",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "5.15.174",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.1.120",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.6.64",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.12.4",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "high",
    "structured": {
      "id": "CVE-2024-56558",
      "aliases": [
        "CVE-2024-56558"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
                {
                  "introduced": "bf18f163e89c52e09c96534db45c4274273a0b34"
                },
                {
                  "fixed": "e2fa0d0e327279a8defb87b263cd0bf288fd9261"
                },
                {
                  "fixed": "7fd29d284b55c2274f7a748e6c5f25b4758b8da5"
                },
                {
                  "fixed": "6cefcadd34e3c71c81ea64b899a0daa86314a51a"
                },
                {
                  "fixed": "7d8f7816bebcd2e7400bb4d786eccb8f33c9f9ec"
                },
                {
                  "fixed": "1cecfdbc6bfc89c516d286884c7f29267b95de2b"
                },
                {
                  "fixed": "7365d1f8de63cffdbbaa2287ce0205438e1a922f"
                },
                {
                  "fixed": "be8f982c369c965faffa198b46060f8853e0f1f0"
                }
              ]
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2024-56558.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "3.17.0"
                },
                {
                  "fixed": "5.4.287"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "5.5.0"
                },
                {
                  "fixed": "5.10.231"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "5.11.0"
                },
                {
                  "fixed": "5.15.174"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "5.16.0"
                },
                {
                  "fixed": "6.1.120"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.2.0"
                },
                {
                  "fixed": "6.6.64"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.7.0"
                },
                {
                  "fixed": "6.12.4"
                }
              ]
            }
          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2024-56558.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:27.468398818Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/1cecfdbc6bfc89c516d286884c7f29267b95de2b",
        "https://git.kernel.org/stable/c/6cefcadd34e3c71c81ea64b899a0daa86314a51a",
        "https://git.kernel.org/stable/c/7365d1f8de63cffdbbaa2287ce0205438e1a922f",
        "https://git.kernel.org/stable/c/7d8f7816bebcd2e7400bb4d786eccb8f33c9f9ec",
        "https://git.kernel.org/stable/c/7fd29d284b55c2274f7a748e6c5f25b4758b8da5",
        "https://git.kernel.org/stable/c/be8f982c369c965faffa198b46060f8853e0f1f0",
        "https://git.kernel.org/stable/c/e2fa0d0e327279a8defb87b263cd0bf288fd9261",
        "https://lists.debian.org/debian-lts-announce/2025/03/msg00001.html",
        "https://lists.debian.org/debian-lts-announce/2025/03/msg00002.html",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2024/56xxx/CVE-2024-56558.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2024-56558",
        "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/2024/56xxx/CVE-2024-56558.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2024-56558",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 493644,
  "published_at": "2024-12-27T14:23:03.902+00:00"
}