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.
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.
Metrics
Affected Vendors & Products
Advisories
No advisories yet.
Fixes
Solution
No solution given by the vendor.
Workaround
No workaround given by the vendor.
References
History
Sat, 06 Dec 2025 00:15:00 +0000
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| References |
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| Metrics |
threat_severity
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cvssV3_1
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Thu, 04 Dec 2025 16:15:00 +0000
| Type | Values Removed | Values Added |
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| Description | 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. | |
| Title | gpio: cdev: make sure the cdev fd is still active before emitting events | |
| First Time appeared |
Linux
Linux linux Kernel |
|
| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Linux
Linux linux Kernel |
|
| References |
|
Projects
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MITRE
Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2025-12-04T16:08:12.206Z
Reserved: 2025-04-16T07:20:57.181Z
Link: CVE-2025-40249
Vulnrichment
No data.
NVD
Status : Awaiting Analysis
Published: 2025-12-04T16:16:18.380
Modified: 2025-12-04T17:15:08.283
Link: CVE-2025-40249
Redhat
OpenCVE Enrichment
No data.
Weaknesses
No weakness.