CVE-2025-68257
Unknown Unknown - Not Provided
BaseFortify

Publication date: 2025-12-16

Last updated on: 2025-12-18

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: comedi: check device's attached status in compat ioctls Syzbot identified an issue [1] that crashes kernel, seemingly due to unexistent callback dev->get_valid_routes(). By all means, this should not occur as said callback must always be set to get_zero_valid_routes() in __comedi_device_postconfig(). As the crash seems to appear exclusively in i386 kernels, at least, judging from [1] reports, the blame lies with compat versions of standard IOCTL handlers. Several of them are modified and do not use comedi_unlocked_ioctl(). While functionality of these ioctls essentially copy their original versions, they do not have required sanity check for device's attached status. This, in turn, leads to a possibility of calling select IOCTLs on a device that has not been properly setup, even via COMEDI_DEVCONFIG. Doing so on unconfigured devices means that several crucial steps are missed, for instance, specifying dev->get_valid_routes() callback. Fix this somewhat crudely by ensuring device's attached status before performing any ioctls, improving logic consistency between modern and compat functions. [1] Syzbot report: BUG: kernel NULL pointer dereference, address: 0000000000000000 ... CR2: ffffffffffffffd6 CR3: 000000006c717000 CR4: 0000000000352ef0 Call Trace: <TASK> get_valid_routes drivers/comedi/comedi_fops.c:1322 [inline] parse_insn+0x78c/0x1970 drivers/comedi/comedi_fops.c:1401 do_insnlist_ioctl+0x272/0x700 drivers/comedi/comedi_fops.c:1594 compat_insnlist drivers/comedi/comedi_fops.c:3208 [inline] comedi_compat_ioctl+0x810/0x990 drivers/comedi/comedi_fops.c:3273 __do_compat_sys_ioctl fs/ioctl.c:695 [inline] __se_compat_sys_ioctl fs/ioctl.c:638 [inline] __ia32_compat_sys_ioctl+0x242/0x370 fs/ioctl.c:638 do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:83 [inline] ...
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Meta Information
Published
2025-12-16
Last Modified
2025-12-18
Generated
2026-05-07
AI Q&A
2025-12-16
EPSS Evaluated
2026-05-05
NVD
CVE-2025-68257
Affected Vendors & Products
Showing 1 associated CPE
Vendor Product Version / Range
linux linux_kernel *
Helpful Resources
Exploitability
CWE
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KEV
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CWE ID Description
CWE-UNKNOWN
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?

This vulnerability occurs in the Linux kernel's comedi subsystem, specifically in the compat ioctl handlers for i386 kernels. The issue is that these compat ioctl functions do not properly check whether a device is attached before performing operations. As a result, IOCTL calls can be made on devices that have not been properly configured, leading to missing crucial setup steps such as setting the dev->get_valid_routes() callback. This can cause a kernel crash due to a NULL pointer dereference when the system tries to call this uninitialized callback.


How can this vulnerability impact me? :

This vulnerability can cause the Linux kernel to crash when certain IOCTL calls are made on unconfigured comedi devices. This can lead to system instability or denial of service, as the kernel encounters a NULL pointer dereference due to missing device setup callbacks.


What immediate steps should I take to mitigate this vulnerability?

The vulnerability can be mitigated by ensuring that the Linux kernel is updated to a version where the fix is applied. The fix involves checking the device's attached status before performing any ioctls, preventing kernel crashes caused by unconfigured devices. Therefore, applying the latest kernel patches or updates that include this fix is the immediate step to mitigate the vulnerability.


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