nfsd: Fix cred ref leak in nfsd_nl_threads_set_doit().

{
  "id": "1a20318a8f12d7732e72ebb74537625a54855c84caed8f7066f6a01de135ff8a",
  "url": "https://osv.dev/vulnerability/CVE-2026-23297",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "nfsd: Fix cred ref leak in nfsd_nl_threads_set_doit().",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: nfsd: Fix cred ref leak in nfsd_nl_threads_set_doit(). syzbot reported memory leak of struct cred. [0] nfsd_nl_threads_set_doit() passes get_current_cred() to nfsd_svc(), but put_cred() is not called after that. The cred is finally passed down to _svc_xprt_create(), which calls get_cred() with the cred for struct svc_xprt. The ownership of the refcount by get_current_cred() is not transferred to anywhere and is just leaked. nfsd_svc() is also called from write_threads(), but it does not bump file->f_cred there. nfsd_nl_threads_set_doit() is called from sendmsg() and current->cred does not go away. Let's use current_cred() in nfsd_nl_threads_set_doit(). [0]: BUG: memory leak unreferenced object 0xffff888108b89480 (size 184): comm \"syz-executor\", pid 5994, jiffies 4294943386 hex dump (first 32 bytes): 01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ backtrace (crc 369454a7): kmemleak_alloc_recursive include/linux/kmemleak.h:44 [inline] slab_post_alloc_hook mm/slub.c:4958 [inline] slab_alloc_node mm/slub.c:5263 [inline] kmem_cache_alloc_noprof+0x412/0x580 mm/slub.c:5270 prepare_creds+0x22/0x600 kernel/cred.c:185 copy_creds+0x44/0x290 kernel/cred.c:286 copy_process+0x7a7/0x2870 kernel/fork.c:2086 kernel_clone+0xac/0x6e0 kernel/fork.c:2651 __do_sys_clone+0x7f/0xb0 kernel/fork.c:2792 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inlin",
    "evidence": "osv:CVE-2026-23297",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "6.12.77",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.18.17",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.19.7",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "CVE-2026-23297",
      "aliases": [
        "CVE-2026-23297"
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
                {
                  "introduced": "924f4fb003ba114c60b3c07a011dcd86a8956cd1"
                },
                {
                  "fixed": "41170716421c25cd20b39e83f0e0762e212b377b"
                },
                {
                  "fixed": "27c13c5bb0948e3b5c64e59f8a903231896fab9b"
                },
                {
                  "fixed": "a3f88e3e18b51a7f654189189c762ebcdeaa7e29"
                },
                {
                  "fixed": "1cb968a2013ffa8112d52ebe605009ea1c6a582c"
                }
              ]
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-23297.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.10.0"
                },
                {
                  "fixed": "6.12.77"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.13.0"
                },
                {
                  "fixed": "6.18.17"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.19.0"
                },
                {
                  "fixed": "6.19.7"
                }
              ]
            }
          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-23297.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:46.089121557Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/1cb968a2013ffa8112d52ebe605009ea1c6a582c",
        "https://git.kernel.org/stable/c/27c13c5bb0948e3b5c64e59f8a903231896fab9b",
        "https://git.kernel.org/stable/c/41170716421c25cd20b39e83f0e0762e212b377b",
        "https://git.kernel.org/stable/c/a3f88e3e18b51a7f654189189c762ebcdeaa7e29",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/23xxx/CVE-2026-23297.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-23297",
        "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/2026/23xxx/CVE-2026-23297.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-23297",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 513987,
  "published_at": "2026-03-25T10:26:54.156+00:00"
}