CVE-2025-40305 (GCVE-0-2025-40305)
Vulnerability from cvelistv5
Published
2025-12-08 00:46
Modified
2026-01-02 15:33
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: 9p/trans_fd: p9_fd_request: kick rx thread if EPOLLIN p9_read_work() doesn't set Rworksched and doesn't do schedule_work(m->rq) if list_empty(&m->req_list). However, if the pipe is full, we need to read more data and this used to work prior to commit aaec5a95d59615 ("pipe_read: don't wake up the writer if the pipe is still full"). p9_read_work() does p9_fd_read() -> ... -> anon_pipe_read() which (before the commit above) triggered the unnecessary wakeup. This wakeup calls p9_pollwake() which kicks p9_poll_workfn() -> p9_poll_mux(), p9_poll_mux() will notice EPOLLIN and schedule_work(&m->rq). This no longer happens after the optimization above, change p9_fd_request() to use p9_poll_mux() instead of only checking for EPOLLOUT.
References
Impacted products
Vendor Product Version
Linux Linux Version: aaec5a95d59615523db03dd53c2052f0a87beea7
Version: aaec5a95d59615523db03dd53c2052f0a87beea7
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          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/9p/trans_fd.c"
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      "descriptions": [
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          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\n9p/trans_fd: p9_fd_request: kick rx thread if EPOLLIN\n\np9_read_work() doesn\u0027t set Rworksched and doesn\u0027t do schedule_work(m-\u003erq)\nif list_empty(\u0026m-\u003ereq_list).\n\nHowever, if the pipe is full, we need to read more data and this used to\nwork prior to commit aaec5a95d59615 (\"pipe_read: don\u0027t wake up the writer\nif the pipe is still full\").\n\np9_read_work() does p9_fd_read() -\u003e ... -\u003e anon_pipe_read() which (before\nthe commit above) triggered the unnecessary wakeup. This wakeup calls\np9_pollwake() which kicks p9_poll_workfn() -\u003e p9_poll_mux(), p9_poll_mux()\nwill notice EPOLLIN and schedule_work(\u0026m-\u003erq).\n\nThis no longer happens after the optimization above, change p9_fd_request()\nto use p9_poll_mux() instead of only checking for EPOLLOUT."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-01-02T15:33:27.804Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
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          "url": "https://git.kernel.org/stable/c/242531004d7de8c159f9bfadebe33fe8060b1046"
        },
        {
          "url": "https://git.kernel.org/stable/c/e8fe3f07a357c39d429e02ca34f740692d88967a"
        }
      ],
      "title": "9p/trans_fd: p9_fd_request: kick rx thread if EPOLLIN",
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  "cveMetadata": {
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    "assignerShortName": "Linux",
    "cveId": "CVE-2025-40305",
    "datePublished": "2025-12-08T00:46:30.327Z",
    "dateReserved": "2025-04-16T07:20:57.185Z",
    "dateUpdated": "2026-01-02T15:33:27.804Z",
    "state": "PUBLISHED"
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  }
}


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