CVE-2025-39927 (GCVE-0-2025-39927)
Vulnerability from cvelistv5
Published
2025-10-01 08:07
Modified
2025-10-02 07:04
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: ceph: fix race condition validating r_parent before applying state Add validation to ensure the cached parent directory inode matches the directory info in MDS replies. This prevents client-side race conditions where concurrent operations (e.g. rename) cause r_parent to become stale between request initiation and reply processing, which could lead to applying state changes to incorrect directory inodes. [ idryomov: folded a kerneldoc fixup and a follow-up fix from Alex to move CEPH_CAP_PIN reference when r_parent is updated: When the parent directory lock is not held, req->r_parent can become stale and is updated to point to the correct inode. However, the associated CEPH_CAP_PIN reference was not being adjusted. The CEPH_CAP_PIN is a reference on an inode that is tracked for accounting purposes. Moving this pin is important to keep the accounting balanced. When the pin was not moved from the old parent to the new one, it created two problems: The reference on the old, stale parent was never released, causing a reference leak. A reference for the new parent was never acquired, creating the risk of a reference underflow later in ceph_mdsc_release_request(). This patch corrects the logic by releasing the pin from the old parent and acquiring it for the new parent when r_parent is switched. This ensures reference accounting stays balanced. ]
References
Impacted products
Vendor Product Version
Linux Linux Version: 9030aaf9bf0a1eee47a154c316c789e959638b0f
Version: 9030aaf9bf0a1eee47a154c316c789e959638b0f
Version: 9030aaf9bf0a1eee47a154c316c789e959638b0f
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{
  "containers": {
    "cna": {
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        {
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          "product": "Linux",
          "programFiles": [
            "fs/ceph/debugfs.c",
            "fs/ceph/dir.c",
            "fs/ceph/file.c",
            "fs/ceph/inode.c",
            "fs/ceph/mds_client.c",
            "fs/ceph/mds_client.h"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
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            "fs/ceph/inode.c",
            "fs/ceph/mds_client.c",
            "fs/ceph/mds_client.h"
          ],
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          "vendor": "Linux",
          "versions": [
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              "version": "2.6.34"
            },
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              "version": "0",
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      "cpeApplicability": [
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              "operator": "OR"
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      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nceph: fix race condition validating r_parent before applying state\n\nAdd validation to ensure the cached parent directory inode matches the\ndirectory info in MDS replies. This prevents client-side race conditions\nwhere concurrent operations (e.g. rename) cause r_parent to become stale\nbetween request initiation and reply processing, which could lead to\napplying state changes to incorrect directory inodes.\n\n[ idryomov: folded a kerneldoc fixup and a follow-up fix from Alex to\n  move CEPH_CAP_PIN reference when r_parent is updated:\n\n  When the parent directory lock is not held, req-\u003er_parent can become\n  stale and is updated to point to the correct inode.  However, the\n  associated CEPH_CAP_PIN reference was not being adjusted.  The\n  CEPH_CAP_PIN is a reference on an inode that is tracked for\n  accounting purposes.  Moving this pin is important to keep the\n  accounting balanced. When the pin was not moved from the old parent\n  to the new one, it created two problems: The reference on the old,\n  stale parent was never released, causing a reference leak.\n  A reference for the new parent was never acquired, creating the risk\n  of a reference underflow later in ceph_mdsc_release_request().  This\n  patch corrects the logic by releasing the pin from the old parent and\n  acquiring it for the new parent when r_parent is switched.  This\n  ensures reference accounting stays balanced. ]"
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2025-10-02T07:04:31.647Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
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          "url": "https://git.kernel.org/stable/c/db378e6f83ec705c6091c65d482d555edc2b0a72"
        },
        {
          "url": "https://git.kernel.org/stable/c/2bfe45987eb346e299d9f763f9cd05f77011519f"
        },
        {
          "url": "https://git.kernel.org/stable/c/15f519e9f883b316d86e2bb6b767a023aafd9d83"
        }
      ],
      "title": "ceph: fix race condition validating r_parent before applying state",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
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    "assignerShortName": "Linux",
    "cveId": "CVE-2025-39927",
    "datePublished": "2025-10-01T08:07:14.595Z",
    "dateReserved": "2025-04-16T07:20:57.147Z",
    "dateUpdated": "2025-10-02T07:04:31.647Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.1",
  "vulnerability-lookup:meta": {
    "nvd": "{\"cve\":{\"id\":\"CVE-2025-39927\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2025-10-01T08:15:36.097\",\"lastModified\":\"2025-10-02T19:12:17.160\",\"vulnStatus\":\"Awaiting Analysis\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"In the Linux kernel, the following vulnerability has been resolved:\\n\\nceph: fix race condition validating r_parent before applying state\\n\\nAdd validation to ensure the cached parent directory inode matches the\\ndirectory info in MDS replies. This prevents client-side race conditions\\nwhere concurrent operations (e.g. rename) cause r_parent to become stale\\nbetween request initiation and reply processing, which could lead to\\napplying state changes to incorrect directory inodes.\\n\\n[ idryomov: folded a kerneldoc fixup and a follow-up fix from Alex to\\n  move CEPH_CAP_PIN reference when r_parent is updated:\\n\\n  When the parent directory lock is not held, req-\u003er_parent can become\\n  stale and is updated to point to the correct inode.  However, the\\n  associated CEPH_CAP_PIN reference was not being adjusted.  The\\n  CEPH_CAP_PIN is a reference on an inode that is tracked for\\n  accounting purposes.  Moving this pin is important to keep the\\n  accounting balanced. When the pin was not moved from the old parent\\n  to the new one, it created two problems: The reference on the old,\\n  stale parent was never released, causing a reference leak.\\n  A reference for the new parent was never acquired, creating the risk\\n  of a reference underflow later in ceph_mdsc_release_request().  This\\n  patch corrects the logic by releasing the pin from the old parent and\\n  acquiring it for the new parent when r_parent is switched.  This\\n  ensures reference accounting stays balanced. ]\"}],\"metrics\":{},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/15f519e9f883b316d86e2bb6b767a023aafd9d83\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/2bfe45987eb346e299d9f763f9cd05f77011519f\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/db378e6f83ec705c6091c65d482d555edc2b0a72\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}"
  }
}


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