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ptp: remove ptp->n_vclocks check logic in ptp_vclock_in_use()

Type: advisorySources: OSV

In the Linux kernel, the following vulnerability has been resolved: ptp: remove ptp->n_vclocks check logic in ptp_vclock_in_use() There is no disagreement that we should check both ptp->is_virtual_clock and ptp->n_vclocks to check if the ptp virtual clock is in use. However, when we acquire ptp->n_vclocks_mux to read ptp->n_vclocks in ptp_vclock_in_use(), we observe a recursive lock in the call trace starting from n_vclocks_store(). ============================================ WARNING: possible recursive locking detected 6.15.0-rc6 #1 Not tainted -------------------------------------------- syz.0.1540/13807 is trying to acquire lock: ffff888035a24868 (&ptp->n_vclocks_mux){+.+.}-{4:4}, at: ptp_vclock_in_use drivers/ptp/ptp_private.h:103 [inline] ffff888035a24868 (&ptp->n_vclocks_mux){+.+.}-{4:4}, at: ptp_clock_unregister+0x21/0x250 drivers/ptp/ptp_clock.c:415 but task is already holding lock: ffff888030704868 (&ptp->n_vclocks_mux){+.+.}-{4:4}, at: n_vclocks_store+0xf1/0x6d0 drivers/ptp/ptp_sysfs.c:215 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(&ptp->n_vclocks_mux); lock(&ptp->n_vclocks_mux); *** DEADLOCK *** .... ============================================ The best way to solve this is to remove the logic that checks ptp->n_vclocks in ptp_vclock_in_use(). The reason why this is appropriate is that any path that uses ptp->n_vclocks must unconditionally check if ptp->n_vclocks is greater than 0 before unregistering vclocks, and al

Products
Kernel
Affected versions
Not specified
Fixed versions
5.15.186, 6.1.142, 6.12.34, 6.15.3, 6.6.94
CVEs
CVE-2025-38305
Confirmed fixed CVEs
Not specified
Updated in this feed
3 Nov 2026, 14:42 UTC · Revision 1

Source evidence

ptp: remove ptp->n_vclocks check logic in ptp_vclock_in_use()

core-osv · Original source

Published 10 Jul 2025, 07:42 UTC

In the Linux kernel, the following vulnerability has been resolved: ptp: remove ptp->n_vclocks check logic in ptp_vclock_in_use() There is no disagreement that we should check both ptp->is_virtual_clock and ptp->n_vclocks to check if the ptp virtual clock is in use. However, when we acquire ptp->n_vclocks_mux to read ptp->n_vclocks in ptp_vclock_in_use(), we observe a recursive lock in the call trace starting from n_vclocks_store(). ============================================ WARNING: possible recursive locking detected 6.15.0-rc6 #1 Not tainted -------------------------------------------- syz.0.1540/13807 is trying to acquire lock: ffff888035a24868 (&ptp->n_vclocks_mux){+.+.}-{4:4}, at: ptp_vclock_in_use drivers/ptp/ptp_private.h:103 [inline] ffff888035a24868 (&ptp->n_vclocks_mux){+.+.}-{4:4}, at: ptp_clock_unregister+0x21/0x250 drivers/ptp/ptp_clock.c:415 but task is already holding lock: ffff888030704868 (&ptp->n_vclocks_mux){+.+.}-{4:4}, at: n_vclocks_store+0xf1/0x6d0 drivers/ptp/ptp_sysfs.c:215 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(&ptp->n_vclocks_mux); lock(&ptp->n_vclocks_mux); *** DEADLOCK *** .... ============================================ The best way to solve this is to remove the logic that checks ptp->n_vclocks in ptp_vclock_in_use(). The reason why this is appropriate is that any path that uses ptp->n_vclocks must unconditionally check if ptp->n_vclocks is greater than 0 before unregistering vclocks, and al

osv:CVE-2025-38305

Kernel

Fixed versions: 5.15.186, 6.1.142, 6.6.94, 6.12.34, 6.15.3

Complete source record
{
  "id": "8e9104fe8a42ffb4100c1005b82d572ec01f4e1cefd8d6739ba5e1242e8fd1ba",
  "url": "https://osv.dev/vulnerability/CVE-2025-38305",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "ptp: remove ptp->n_vclocks check logic in ptp_vclock_in_use()",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: ptp: remove ptp->n_vclocks check logic in ptp_vclock_in_use() There is no disagreement that we should check both ptp->is_virtual_clock and ptp->n_vclocks to check if the ptp virtual clock is in use. However, when we acquire ptp->n_vclocks_mux to read ptp->n_vclocks in ptp_vclock_in_use(), we observe a recursive lock in the call trace starting from n_vclocks_store(). ============================================ WARNING: possible recursive locking detected 6.15.0-rc6 #1 Not tainted -------------------------------------------- syz.0.1540/13807 is trying to acquire lock: ffff888035a24868 (&ptp->n_vclocks_mux){+.+.}-{4:4}, at: ptp_vclock_in_use drivers/ptp/ptp_private.h:103 [inline] ffff888035a24868 (&ptp->n_vclocks_mux){+.+.}-{4:4}, at: ptp_clock_unregister+0x21/0x250 drivers/ptp/ptp_clock.c:415 but task is already holding lock: ffff888030704868 (&ptp->n_vclocks_mux){+.+.}-{4:4}, at: n_vclocks_store+0xf1/0x6d0 drivers/ptp/ptp_sysfs.c:215 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(&ptp->n_vclocks_mux); lock(&ptp->n_vclocks_mux); *** DEADLOCK *** .... ============================================ The best way to solve this is to remove the logic that checks ptp->n_vclocks in ptp_vclock_in_use(). The reason why this is appropriate is that any path that uses ptp->n_vclocks must unconditionally check if ptp->n_vclocks is greater than 0 before unregistering vclocks, and al",
    "evidence": "osv:CVE-2025-38305",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "5.15.186",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.1.142",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.6.94",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.12.34",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.15.3",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "CVE-2025-38305",
      "aliases": [
        "CVE-2025-38305"
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
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                },
                {
                  "fixed": "5d217e7031a5c06d366580fc6ddbf43527b780d4"
                },
                {
                  "fixed": "b1b73c452331451020be3bf4b014901015ae6663"
                },
                {
                  "fixed": "259119595227fd20f6aa29d85abe086b6fdd9eb1"
                },
                {
                  "fixed": "b93e6fef4eda48e17d9c642b9abad98a066fd4a3"
                },
                {
                  "fixed": "ef8fc007c28a30a4c0d90bf755e0f343d99bb392"
                },
                {
                  "fixed": "87f7ce260a3c838b49e1dc1ceedf1006795157a2"
                }
              ]
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2025-38305.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "5.14.0"
                },
                {
                  "fixed": "5.15.186"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "5.16.0"
                },
                {
                  "fixed": "6.1.142"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.2.0"
                },
                {
                  "fixed": "6.6.94"
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              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.7.0"
                },
                {
                  "fixed": "6.12.34"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.13.0"
                },
                {
                  "fixed": "6.15.3"
                }
              ]
            }
          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2025-38305.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:29.938905734Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/259119595227fd20f6aa29d85abe086b6fdd9eb1",
        "https://git.kernel.org/stable/c/5d217e7031a5c06d366580fc6ddbf43527b780d4",
        "https://git.kernel.org/stable/c/87f7ce260a3c838b49e1dc1ceedf1006795157a2",
        "https://git.kernel.org/stable/c/b1b73c452331451020be3bf4b014901015ae6663",
        "https://git.kernel.org/stable/c/b93e6fef4eda48e17d9c642b9abad98a066fd4a3",
        "https://git.kernel.org/stable/c/ef8fc007c28a30a4c0d90bf755e0f343d99bb392",
        "https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/38xxx/CVE-2025-38305.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2025-38305",
        "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/2025/38xxx/CVE-2025-38305.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2025-38305",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 496464,
  "published_at": "2025-07-10T07:42:16.127+00:00"
}