CVE-2025-40039 (GCVE-0-2025-40039)
Vulnerability from cvelistv5
Published
2025-10-28 11:48
Modified
2025-10-28 11:48
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: ksmbd: Fix race condition in RPC handle list access The 'sess->rpc_handle_list' XArray manages RPC handles within a ksmbd session. Access to this list is intended to be protected by 'sess->rpc_lock' (an rw_semaphore). However, the locking implementation was flawed, leading to potential race conditions. In ksmbd_session_rpc_open(), the code incorrectly acquired only a read lock before calling xa_store() and xa_erase(). Since these operations modify the XArray structure, a write lock is required to ensure exclusive access and prevent data corruption from concurrent modifications. Furthermore, ksmbd_session_rpc_method() accessed the list using xa_load() without holding any lock at all. This could lead to reading inconsistent data or a potential use-after-free if an entry is concurrently removed and the pointer is dereferenced. Fix these issues by: 1. Using down_write() and up_write() in ksmbd_session_rpc_open() to ensure exclusive access during XArray modification, and ensuring the lock is correctly released on error paths. 2. Adding down_read() and up_read() in ksmbd_session_rpc_method() to safely protect the lookup.
References
Impacted products
Vendor Product Version
Linux Linux Version: b685757c7b08d5073046fb379be965fd6c06aafc
Version: b685757c7b08d5073046fb379be965fd6c06aafc
Version: b685757c7b08d5073046fb379be965fd6c06aafc
Version: 1f485b54d04a920723984062c912174330a05178
Version: 052b41ef2abe274f068e892aee81406f11bd1f3a
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{
  "containers": {
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          "product": "Linux",
          "programFiles": [
            "fs/smb/server/mgmt/user_session.c"
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          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: Fix race condition in RPC handle list access\n\nThe \u0027sess-\u003erpc_handle_list\u0027 XArray manages RPC handles within a ksmbd\nsession. Access to this list is intended to be protected by\n\u0027sess-\u003erpc_lock\u0027 (an rw_semaphore). However, the locking implementation was\nflawed, leading to potential race conditions.\n\nIn ksmbd_session_rpc_open(), the code incorrectly acquired only a read lock\nbefore calling xa_store() and xa_erase(). Since these operations modify\nthe XArray structure, a write lock is required to ensure exclusive access\nand prevent data corruption from concurrent modifications.\n\nFurthermore, ksmbd_session_rpc_method() accessed the list using xa_load()\nwithout holding any lock at all. This could lead to reading inconsistent\ndata or a potential use-after-free if an entry is concurrently removed and\nthe pointer is dereferenced.\n\nFix these issues by:\n1. Using down_write() and up_write() in ksmbd_session_rpc_open()\n   to ensure exclusive access during XArray modification, and ensuring\n   the lock is correctly released on error paths.\n2. Adding down_read() and up_read() in ksmbd_session_rpc_method()\n   to safely protect the lookup."
        }
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        "dateUpdated": "2025-10-28T11:48:19.781Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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        },
        {
          "url": "https://git.kernel.org/stable/c/305853cce379407090a73b38c5de5ba748893aee"
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      ],
      "title": "ksmbd: Fix race condition in RPC handle list access",
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  "cveMetadata": {
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    "assignerShortName": "Linux",
    "cveId": "CVE-2025-40039",
    "datePublished": "2025-10-28T11:48:19.781Z",
    "dateReserved": "2025-04-16T07:20:57.153Z",
    "dateUpdated": "2025-10-28T11:48:19.781Z",
    "state": "PUBLISHED"
  },
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    "nvd": "{\"cve\":{\"id\":\"CVE-2025-40039\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2025-10-28T12:15:37.847\",\"lastModified\":\"2025-10-30T15:05:32.197\",\"vulnStatus\":\"Awaiting Analysis\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"In the Linux kernel, the following vulnerability has been resolved:\\n\\nksmbd: Fix race condition in RPC handle list access\\n\\nThe \u0027sess-\u003erpc_handle_list\u0027 XArray manages RPC handles within a ksmbd\\nsession. Access to this list is intended to be protected by\\n\u0027sess-\u003erpc_lock\u0027 (an rw_semaphore). However, the locking implementation was\\nflawed, leading to potential race conditions.\\n\\nIn ksmbd_session_rpc_open(), the code incorrectly acquired only a read lock\\nbefore calling xa_store() and xa_erase(). Since these operations modify\\nthe XArray structure, a write lock is required to ensure exclusive access\\nand prevent data corruption from concurrent modifications.\\n\\nFurthermore, ksmbd_session_rpc_method() accessed the list using xa_load()\\nwithout holding any lock at all. This could lead to reading inconsistent\\ndata or a potential use-after-free if an entry is concurrently removed and\\nthe pointer is dereferenced.\\n\\nFix these issues by:\\n1. Using down_write() and up_write() in ksmbd_session_rpc_open()\\n   to ensure exclusive access during XArray modification, and ensuring\\n   the lock is correctly released on error paths.\\n2. Adding down_read() and up_read() in ksmbd_session_rpc_method()\\n   to safely protect the lookup.\"}],\"metrics\":{},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/305853cce379407090a73b38c5de5ba748893aee\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/5cc679ba0f4505936124cd4179ba66bb0a4bd9f3\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/6bd7e0e55dcea2cf0d391bbc21c2eb069b4be3e1\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}"
  }
}


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