CVE-2025-40249 (GCVE-0-2025-40249)

Vulnerability from cvelistv5 – Published: 2025-12-04 16:08 – Updated: 2025-12-04 16:08
VLAI?
Title
gpio: cdev: make sure the cdev fd is still active before emitting events
Summary
In the Linux kernel, the following vulnerability has been resolved: gpio: cdev: make sure the cdev fd is still active before emitting events With the final call to fput() on a file descriptor, the release action may be deferred and scheduled on a work queue. The reference count of that descriptor is still zero and it must not be used. It's possible that a GPIO change, we want to notify the user-space about, happens AFTER the reference count on the file descriptor associated with the character device went down to zero but BEFORE the .release() callback was called from the workqueue and so BEFORE we unregistered from the notifier. Using the regular get_file() routine in this situation triggers the following warning: struct file::f_count incremented from zero; use-after-free condition present! So use the get_file_active() variant that will return NULL on file descriptors that have been or are being released.
Severity ?
No CVSS data available.
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: 40b7c49950bd56c984b1f6722f865b922879260e , < dccc6daa8afa0f64c432e4c867f275747e3415e1 (git)
Affected: 40b7c49950bd56c984b1f6722f865b922879260e , < d4cd0902c156b2ca60fdda8cd8b5bcb4b0e9ed64 (git)
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    Linux Linux Affected: 6.13
Unaffected: 0 , < 6.13 (semver)
Unaffected: 6.17.10 , ≤ 6.17.* (semver)
Unaffected: 6.18 , ≤ * (original_commit_for_fix)
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          "programFiles": [
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ngpio: cdev: make sure the cdev fd is still active before emitting events\n\nWith the final call to fput() on a file descriptor, the release action\nmay be deferred and scheduled on a work queue. The reference count of\nthat descriptor is still zero and it must not be used. It\u0027s possible\nthat a GPIO change, we want to notify the user-space about, happens\nAFTER the reference count on the file descriptor associated with the\ncharacter device went down to zero but BEFORE the .release() callback\nwas called from the workqueue and so BEFORE we unregistered from the\nnotifier.\n\nUsing the regular get_file() routine in this situation triggers the\nfollowing warning:\n\n  struct file::f_count incremented from zero; use-after-free condition present!\n\nSo use the get_file_active() variant that will return NULL on file\ndescriptors that have been or are being released."
        }
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      "providerMetadata": {
        "dateUpdated": "2025-12-04T16:08:12.206Z",
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        "shortName": "Linux"
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    "cveId": "CVE-2025-40249",
    "datePublished": "2025-12-04T16:08:12.206Z",
    "dateReserved": "2025-04-16T07:20:57.181Z",
    "dateUpdated": "2025-12-04T16:08:12.206Z",
    "state": "PUBLISHED"
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    "nvd": "{\"cve\":{\"id\":\"CVE-2025-40249\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2025-12-04T16:16:18.380\",\"lastModified\":\"2025-12-04T17:15:08.283\",\"vulnStatus\":\"Awaiting Analysis\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"In the Linux kernel, the following vulnerability has been resolved:\\n\\ngpio: cdev: make sure the cdev fd is still active before emitting events\\n\\nWith the final call to fput() on a file descriptor, the release action\\nmay be deferred and scheduled on a work queue. The reference count of\\nthat descriptor is still zero and it must not be used. It\u0027s possible\\nthat a GPIO change, we want to notify the user-space about, happens\\nAFTER the reference count on the file descriptor associated with the\\ncharacter device went down to zero but BEFORE the .release() callback\\nwas called from the workqueue and so BEFORE we unregistered from the\\nnotifier.\\n\\nUsing the regular get_file() routine in this situation triggers the\\nfollowing warning:\\n\\n  struct file::f_count incremented from zero; use-after-free condition present!\\n\\nSo use the get_file_active() variant that will return NULL on file\\ndescriptors that have been or are being released.\"}],\"metrics\":{},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/d4cd0902c156b2ca60fdda8cd8b5bcb4b0e9ed64\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/dccc6daa8afa0f64c432e4c867f275747e3415e1\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}"
  }
}


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