CVE-2025-40039 (GCVE-0-2025-40039)

Vulnerability from cvelistv5 – Published: 2025-10-28 11:48 – Updated: 2025-12-01 06:16
VLAI?
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.
Severity ?
No CVSS data available.
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: b685757c7b08d5073046fb379be965fd6c06aafc , < 5cc679ba0f4505936124cd4179ba66bb0a4bd9f3 (git)
Affected: b685757c7b08d5073046fb379be965fd6c06aafc , < 6bd7e0e55dcea2cf0d391bbc21c2eb069b4be3e1 (git)
Affected: b685757c7b08d5073046fb379be965fd6c06aafc , < 305853cce379407090a73b38c5de5ba748893aee (git)
Affected: 1f485b54d04a920723984062c912174330a05178 (git)
Affected: 052b41ef2abe274f068e892aee81406f11bd1f3a (git)
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    Linux Linux Affected: 6.3
Unaffected: 0 , < 6.3 (semver)
Unaffected: 6.12.53 , ≤ 6.12.* (semver)
Unaffected: 6.17.3 , ≤ 6.17.* (semver)
Unaffected: 6.18 , ≤ * (original_commit_for_fix)
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{
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          "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": "2025-12-01T06:16:43.388Z",
        "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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    "assignerShortName": "Linux",
    "cveId": "CVE-2025-40039",
    "datePublished": "2025-10-28T11:48:19.781Z",
    "dateReserved": "2025-04-16T07:20:57.153Z",
    "dateUpdated": "2025-12-01T06:16:43.388Z",
    "state": "PUBLISHED"
  },
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  • Confirmed: The vulnerability has been validated from an analyst's perspective.
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