CVE-2025-39684:A kernel information leak vulnerability in the Linux kernel's comedi subsystem due to uninitialized memory usage in do_insn_ioctl() and do_insnlist_ioctl() functions.

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CVE-2025-39684 addresses a vulnerability in the Linux kernel's comedi subsystem where uninitialized memory is used in the do_insn_ioctl() and do_insnlist_ioctl() functions. This issue can lead to information leaks, potentially exposing sensitive kernel data to user-space applications. The vulnerability stems from certain instruction handlers not fully populating the allocated buffer with data before it's copied back to user-space, resulting in the disclosure of uninitialized kernel memory.

Overview

The vulnerability affects the comedi subsystem in the Linux kernel. It arises from incomplete buffer initialization in the do_insn_ioctl() and do_insnlist_ioctl() functions. Two specific cases were identified: the insn_rw_emulate_bits() function, which only fills in at most one sample for INSN_READ instructions, and the vm80xx_ai_insn_read() function in the "vm80xx" driver, which doesn't properly handle error cases. These issues can lead to the exposure of uninitialized kernel memory to user-space, potentially revealing sensitive information.

Remediation

To address this vulnerability, the Linux kernel developers have implemented fixes in do_insn_ioctl() and do_insnlist_ioctl() functions. The solution ensures that uninitialized parts of the allocated buffer are zeroed before handling each instruction. This prevents the leakage of uninitialized kernel memory to user-space. System administrators and users should update their Linux kernel to the latest version that includes these fixes to mitigate the risk associated with this vulnerability.

References

[1] Linux kernel stable tree commit 3cd212e895ca2d58963fdc6422502b10dd3966bb [2] Linux kernel stable tree commit 868a1b68dcd9f2805bb86aa64862402f785d8c4a [3] Linux kernel stable tree commit aecf0d557ddd95ce68193a5ee1dc4c87415ff08a [4] Linux kernel stable tree commit d84f6e77ebe3359394df32ecd97e0d76a25283dc [5] Linux kernel stable tree commit f3b0c9ec54736f3b8118f93a473d22e11ee65743 [6] Linux kernel stable tree commit ff4a7c18799c7fe999fa56c5cf276e13866b8c1a

Industry ExposureMost to least
This section illustrates the prevalence of a specific Common Vulnerabilities and Exposures (CVE) across various industries based on customer reports. The ranking displays industries from the most to least affected by this particular vulnerability, offering valuable insight into where this CVE has been most frequently observed. This information can help organizations within these sectors prioritize their security efforts, understand their relative risk exposure compared to their peers, and focus remediation strategies where they are most needed. By understanding the industry-specific impact, organizations can make more informed decisions regarding patching, resource allocation, and overall risk management related to this CVE.

  1. Manufacturing: Medium
    Manufacturing
  2. Health Care & Social Assistance: Medium
    Health Care & Social Assistance
  3. Public Administration: Medium
    Public Administration
  4. Professional, Scientific, & Technical Services: Low
    Professional, Scientific, & Technical Services
  5. Educational Services: Low
    Educational Services
  6. Finance and Insurance: Low
    Finance and Insurance
  7. Transportation & Warehousing: Low
    Transportation & Warehousing
  8. Management of Companies & Enterprises: Low
    Management of Companies & Enterprises
  9. Arts, Entertainment & Recreation: Low
    Arts, Entertainment & Recreation
  10. Other Services (except Public Administration): Low
    Other Services (except Public Administration)
  11. Retail Trade: Low
    Retail Trade
  12. Utilities: Low
    Utilities
  13. Agriculture, Forestry Fishing & Hunting: Low
    Agriculture, Forestry Fishing & Hunting
  14. Information: Low
    Information
  15. Real Estate Rental & Leasing: Low
    Real Estate Rental & Leasing
  16. Accommodation & Food Services: Low
    Accommodation & Food Services
  17. Administrative, Support, Waste Management & Remediation Services: Low
    Administrative, Support, Waste Management & Remediation Services
  18. Construction: Low
    Construction
  19. Mining: Low
    Mining
  20. Wholesale Trade: Low
    Wholesale Trade

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