CVE-2025-68335: comedi: pcl818: fix null-ptr-deref in pcl818_ai_cancel()
In the Linux kernel, the following vulnerability has been resolved:
comedi: pcl818: fix null-ptr-deref in pcl818aicancel()
Syzbot identified an issue [1] in pcl818aicancel(), which stems from the fact that in case of early device detach via pcl818detach(), subdevice dev->readsubdev may not have initialized its pointer to &struct comediasync as intended. Thus, any such dereferencing of &s->async->cmd will lead to general protection fault and kernel crash.
Mitigate this problem by removing a call to pcl818aicancel() from pcl818detach() altogether. This way, if the subdevice setups its support for async commands, everything async-related will be handled via subdevice's own ->cancel() function in comedidevicedetachlocked() even before pcl818detach(). If no support for asynchronous commands is provided, there is no need to cancel anything either.
[1] Syzbot crash: Oops: general protection fault, probably for non-canonical address 0xdffffc0000000005: 0000 [#1] SMP KASAN PTI KASAN: null-ptr-deref in range [0x0000000000000028-0x000000000000002f] CPU: 1 UID: 0 PID: 6050 Comm: syz.0.18 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025 RIP: 0010:pcl818aicancel+0x69/0x3f0 drivers/comedi/drivers/pcl818.c:762 ... Call Trace: <TASK> pcl818detach+0x66/0xd0 drivers/comedi/drivers/pcl818.c:1115 comedidevicedetachlocked+0x178/0x750 drivers/comedi/drivers.c:207 dodevconfigioctl drivers/comedi/comedifops.c:848 [inline] comediunlockedioctl+0xcde/0x1020 drivers/comedi/comedifops.c:2178 vfsioctl fs/ioctl.c:51 [inline] dosysioctl fs/ioctl.c:597 [inline] ...
Affected Software
Remediation
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debian/linuxto a version that resolves this vulnerability.Fixed in 6.1.176-1Fixed in 6.1.190-1Fixed in 6.12.107-1Fixed in 6.12.116-1Fixed in 7.2.15-1Fixed in 7.3.4-1 - Compensating control
In the Linux kernel comedi pcl818 driver, remove the call to pcl818_ai_cancel() from pcl818_detach(); asynchronous operations are handled by the subdevice's own ->cancel() function during comedi_device_detach_locked().
Event History
Frequently Asked Questions
What is the severity of CVE-2025-68335?
CVE-2025-68335 is considered to have a low severity level due to its specific circumstances related to early device detach.
How do I fix CVE-2025-68335?
To resolve CVE-2025-68335, update your Linux kernel to the latest stable version that contains the patch addressing this vulnerability.
What component is affected by CVE-2025-68335?
CVE-2025-68335 affects the Linux kernel's comedi driver, specifically the pcl818 subdevice.
How can CVE-2025-68335 impact system stability?
CVE-2025-68335 can lead to a null pointer dereference, potentially causing system crashes or instability when the affected driver is in use.
What versions of the Linux kernel are vulnerable to CVE-2025-68335?
CVE-2025-68335 affects versions of the Linux kernel prior to the application of the specific patch that addresses this issue.