CVE-2025-38687

In the Linux kernel, the following vulnerability has been resolved: comedi: fix race between polling and detaching syzbot reports a use-after-free in comedi in the below link, which is due to comedi gladly removing the allocated async area even though poll requests are still active on the wait_queue_head inside of it. This can cause a use-after-free when the poll entries are later triggered or removed, as the memory for the wait_queue_head has been freed. We need to check there are no tasks queued on any of the subdevices' wait queues before allowing the device to be detached by the `COMEDI_DEVCONFIG` ioctl. Tasks will read-lock `dev->attach_lock` before adding themselves to the subdevice wait queue, so fix the problem in the `COMEDI_DEVCONFIG` ioctl handler by write-locking `dev->attach_lock` before checking that all of the subdevices are safe to be deleted. This includes testing for any sleepers on the subdevices' wait queues. It remains locked until the device has been detached. This requires the `comedi_device_detach()` function to be refactored slightly, moving the bulk of it into new function `comedi_device_detach_locked()`. Note that the refactor of `comedi_device_detach()` results in `comedi_device_cancel_all()` now being called while `dev->attach_lock` is write-locked, which wasn't the case previously, but that does not matter. Thanks to Jens Axboe for diagnosing the problem and co-developing this patch.
Configurations

Configuration 1 (hide)

OR cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*

Configuration 2 (hide)

cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:*

History

09 Jan 2026, 19:00

Type Values Removed Values Added
CVSS v2 : unknown
v3 : unknown
v2 : unknown
v3 : 4.7
CPE cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
References () https://git.kernel.org/stable/c/017198079551a2a5cf61eae966af3c4b145e1f3b - () https://git.kernel.org/stable/c/017198079551a2a5cf61eae966af3c4b145e1f3b - Patch
References () https://git.kernel.org/stable/c/0f989f9d05492028afd2bded4b42023c57d8a76e - () https://git.kernel.org/stable/c/0f989f9d05492028afd2bded4b42023c57d8a76e - Patch
References () https://git.kernel.org/stable/c/35b6fc51c666fc96355be5cd633ed0fe4ccf68b2 - () https://git.kernel.org/stable/c/35b6fc51c666fc96355be5cd633ed0fe4ccf68b2 - Patch
References () https://git.kernel.org/stable/c/5724e82df4f9a4be62908362c97d522d25de75dd - () https://git.kernel.org/stable/c/5724e82df4f9a4be62908362c97d522d25de75dd - Patch
References () https://git.kernel.org/stable/c/5c4a2ffcbd052c69bbf4680677d4c4eaa5a252d4 - () https://git.kernel.org/stable/c/5c4a2ffcbd052c69bbf4680677d4c4eaa5a252d4 - Patch
References () https://git.kernel.org/stable/c/71ca60d2e631cf9c63bcbc7017961c61ff04e419 - () https://git.kernel.org/stable/c/71ca60d2e631cf9c63bcbc7017961c61ff04e419 - Patch
References () https://git.kernel.org/stable/c/cd4286123d6948ff638ea9cd5818ae4796d5d252 - () https://git.kernel.org/stable/c/cd4286123d6948ff638ea9cd5818ae4796d5d252 - Patch
References () https://git.kernel.org/stable/c/d85fac8729c9acfd72368faff1d576ec585e5c8f - () https://git.kernel.org/stable/c/d85fac8729c9acfd72368faff1d576ec585e5c8f - Patch
References () https://git.kernel.org/stable/c/fe67122ba781df44a1a9716eb1dfd751321ab512 - () https://git.kernel.org/stable/c/fe67122ba781df44a1a9716eb1dfd751321ab512 - Patch
References () https://lists.debian.org/debian-lts-announce/2025/10/msg00007.html - () https://lists.debian.org/debian-lts-announce/2025/10/msg00007.html - Third Party Advisory
References () https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html - () https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html - Third Party Advisory
First Time Linux
Debian
Debian debian Linux
Linux linux Kernel
CWE CWE-362

03 Nov 2025, 18:16

Type Values Removed Values Added
References
  • () https://lists.debian.org/debian-lts-announce/2025/10/msg00007.html -
  • () https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html -

04 Sep 2025, 16:15

Type Values Removed Values Added
New CVE

Information

Published : 2025-09-04 16:15

Updated : 2026-01-09 19:00


NVD link : CVE-2025-38687

Mitre link : CVE-2025-38687

CVE.ORG link : CVE-2025-38687


JSON object : View

Products Affected

debian

  • debian_linux

linux

  • linux_kernel
CWE
CWE-362

Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')