Bug 2464497 (CVE-2026-31751)

Summary: CVE-2026-31751 kernel: comedi: dt2815: add hardware detection to prevent crash
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
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Priority: unspecified    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel's comedi dt2815 driver. A local user can exploit this vulnerability by attaching the driver to arbitrary I/O addresses without actual hardware present. This can trigger a page fault during output operations on non-existent hardware, leading to a kernel crash. This issue results in a denial of service.
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Description OSIDB Bzimport 2026-05-01 15:10:05 UTC 
In the Linux kernel, the following vulnerability has been resolved:

comedi: dt2815: add hardware detection to prevent crash

The dt2815 driver crashes when attached to I/O ports without actual
hardware present. This occurs because syzkaller or users can attach
the driver to arbitrary I/O addresses via COMEDI_DEVCONFIG ioctl.

When no hardware exists at the specified port, inb() operations return
0xff (floating bus), but outb() operations can trigger page faults due
to undefined behavior, especially under race conditions:

  BUG: unable to handle page fault for address: 000000007fffff90
  #PF: supervisor write access in kernel mode
  #PF: error_code(0x0002) - not-present page
  RIP: 0010:dt2815_attach+0x6e0/0x1110

Add hardware detection by reading the status register before attempting
any write operations. If the read returns 0xff, assume no hardware is
present and fail the attach with -ENODEV. This prevents crashes from
outb() operations on non-existent hardware.
Comment 1 Keith Grant 2026-05-01 22:06:19 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026050142-CVE-2026-31751-f6c7@gregkh/T