CVE-2025-40002 (GCVE-0-2025-40002)
Vulnerability from cvelistv5
Published
2025-10-18 08:03
Modified
2025-10-18 08:03
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: thunderbolt: Fix use-after-free in tb_dp_dprx_work The original code relies on cancel_delayed_work() in tb_dp_dprx_stop(), which does not ensure that the delayed work item tunnel->dprx_work has fully completed if it was already running. This leads to use-after-free scenarios where tb_tunnel is deallocated by tb_tunnel_put(), while tunnel->dprx_work remains active and attempts to dereference tb_tunnel in tb_dp_dprx_work(). A typical race condition is illustrated below: CPU 0 | CPU 1 tb_dp_tunnel_active() | tb_deactivate_and_free_tunnel()| tb_dp_dprx_start() tb_tunnel_deactivate() | queue_delayed_work() tb_dp_activate() | tb_dp_dprx_stop() | tb_dp_dprx_work() //delayed worker cancel_delayed_work() | tb_tunnel_put(tunnel); | | tunnel = container_of(...); //UAF | tunnel-> //UAF Replacing cancel_delayed_work() with cancel_delayed_work_sync() is not feasible as it would introduce a deadlock: both tb_dp_dprx_work() and the cleanup path acquire tb->lock, and cancel_delayed_work_sync() would wait indefinitely for the work item that cannot proceed. Instead, implement proper reference counting: - If cancel_delayed_work() returns true (work is pending), we release the reference in the stop function. - If it returns false (work is executing or already completed), the reference is released in delayed work function itself. This ensures the tb_tunnel remains valid during work item execution while preventing memory leaks. This bug was found by static analysis.
References
Impacted products
Vendor Product Version
Linux Linux Version: d6d458d42e1e1544a18f37f1d5c840e00d5261b9
Version: d6d458d42e1e1544a18f37f1d5c840e00d5261b9
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{
  "containers": {
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      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/thunderbolt/tunnel.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
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          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
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              "version": "0",
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              "status": "unaffected",
              "version": "6.18-rc1",
              "versionType": "original_commit_for_fix"
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      "cpeApplicability": [
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          "nodes": [
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                  "versionEndExcluding": "6.17.3",
                  "versionStartIncluding": "6.14",
                  "vulnerable": true
                },
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      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nthunderbolt: Fix use-after-free in tb_dp_dprx_work\n\nThe original code relies on cancel_delayed_work() in tb_dp_dprx_stop(),\nwhich does not ensure that the delayed work item tunnel-\u003edprx_work has\nfully completed if it was already running. This leads to use-after-free\nscenarios where tb_tunnel is deallocated by tb_tunnel_put(), while\ntunnel-\u003edprx_work remains active and attempts to dereference tb_tunnel\nin tb_dp_dprx_work().\n\nA typical race condition is illustrated below:\n\nCPU 0                            | CPU 1\ntb_dp_tunnel_active()            |\n  tb_deactivate_and_free_tunnel()| tb_dp_dprx_start()\n    tb_tunnel_deactivate()       |   queue_delayed_work()\n      tb_dp_activate()           |\n        tb_dp_dprx_stop()        | tb_dp_dprx_work() //delayed worker\n          cancel_delayed_work()  |\n    tb_tunnel_put(tunnel);       |\n                                 |   tunnel = container_of(...); //UAF\n                                 |   tunnel-\u003e //UAF\n\nReplacing cancel_delayed_work() with cancel_delayed_work_sync() is\nnot feasible as it would introduce a deadlock: both tb_dp_dprx_work()\nand the cleanup path acquire tb-\u003elock, and cancel_delayed_work_sync()\nwould wait indefinitely for the work item that cannot proceed.\n\nInstead, implement proper reference counting:\n- If cancel_delayed_work() returns true (work is pending), we release\n  the reference in the stop function.\n- If it returns false (work is executing or already completed), the\n  reference is released in delayed work function itself.\n\nThis ensures the tb_tunnel remains valid during work item execution\nwhile preventing memory leaks.\n\nThis bug was found by static analysis."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2025-10-18T08:03:22.718Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/c07923f6a8729fc27ee652221a51702ff6654097"
        },
        {
          "url": "https://git.kernel.org/stable/c/67600ccfc4f38ebd331b9332ac94717bfbc87ea7"
        }
      ],
      "title": "thunderbolt: Fix use-after-free in tb_dp_dprx_work",
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  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2025-40002",
    "datePublished": "2025-10-18T08:03:22.718Z",
    "dateReserved": "2025-04-16T07:20:57.151Z",
    "dateUpdated": "2025-10-18T08:03:22.718Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.1",
  "vulnerability-lookup:meta": {
    "nvd": "{\"cve\":{\"id\":\"CVE-2025-40002\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2025-10-18T08:15:34.243\",\"lastModified\":\"2025-10-21T19:31:25.450\",\"vulnStatus\":\"Awaiting Analysis\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"In the Linux kernel, the following vulnerability has been resolved:\\n\\nthunderbolt: Fix use-after-free in tb_dp_dprx_work\\n\\nThe original code relies on cancel_delayed_work() in tb_dp_dprx_stop(),\\nwhich does not ensure that the delayed work item tunnel-\u003edprx_work has\\nfully completed if it was already running. This leads to use-after-free\\nscenarios where tb_tunnel is deallocated by tb_tunnel_put(), while\\ntunnel-\u003edprx_work remains active and attempts to dereference tb_tunnel\\nin tb_dp_dprx_work().\\n\\nA typical race condition is illustrated below:\\n\\nCPU 0                            | CPU 1\\ntb_dp_tunnel_active()            |\\n  tb_deactivate_and_free_tunnel()| tb_dp_dprx_start()\\n    tb_tunnel_deactivate()       |   queue_delayed_work()\\n      tb_dp_activate()           |\\n        tb_dp_dprx_stop()        | tb_dp_dprx_work() //delayed worker\\n          cancel_delayed_work()  |\\n    tb_tunnel_put(tunnel);       |\\n                                 |   tunnel = container_of(...); //UAF\\n                                 |   tunnel-\u003e //UAF\\n\\nReplacing cancel_delayed_work() with cancel_delayed_work_sync() is\\nnot feasible as it would introduce a deadlock: both tb_dp_dprx_work()\\nand the cleanup path acquire tb-\u003elock, and cancel_delayed_work_sync()\\nwould wait indefinitely for the work item that cannot proceed.\\n\\nInstead, implement proper reference counting:\\n- If cancel_delayed_work() returns true (work is pending), we release\\n  the reference in the stop function.\\n- If it returns false (work is executing or already completed), the\\n  reference is released in delayed work function itself.\\n\\nThis ensures the tb_tunnel remains valid during work item execution\\nwhile preventing memory leaks.\\n\\nThis bug was found by static analysis.\"}],\"metrics\":{},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/67600ccfc4f38ebd331b9332ac94717bfbc87ea7\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/c07923f6a8729fc27ee652221a51702ff6654097\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}"
  }
}


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