CVE-2026-31750
Analyzed Analyzed - Analysis Complete
Memory Leak in Linux Kernel Comedi Subsystem

Publication date: 2026-05-01

Last updated on: 2026-05-07

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: comedi: runflags cannot determine whether to reclaim chanlist syzbot reported a memory leak [1], because commit 4e1da516debb ("comedi: Add reference counting for Comedi command handling") did not consider the exceptional exit case in do_cmd_ioctl() where runflags is not set. This caused chanlist not to be properly freed by do_become_nonbusy(), as it only frees chanlist when runflags is correctly set. Added a check in do_become_nonbusy() for the case where runflags is not set, to properly free the chanlist memory. [1] BUG: memory leak backtrace (crc 844a0efa): __comedi_get_user_chanlist drivers/comedi/comedi_fops.c:1815 [inline] do_cmd_ioctl.part.0+0x112/0x350 drivers/comedi/comedi_fops.c:1890 do_cmd_ioctl drivers/comedi/comedi_fops.c:1858 [inline]
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Meta Information
Published
2026-05-01
Last Modified
2026-05-07
Generated
2026-06-16
AI Q&A
2026-05-01
EPSS Evaluated
2026-06-15
NVD
CVE-2026-31750
EUVD
EUVD-2026-26563
Affected Vendors & Products
Showing 7 associated CPEs
Vendor Product Version / Range
linux linux_kernel 7.0
linux linux_kernel 7.0
linux linux_kernel 7.0
linux linux_kernel 7.0
linux linux_kernel 7.0
linux linux_kernel 7.0
linux linux_kernel From 6.19 (inc) to 6.19.12 (exc)
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Exploitability
CWE
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KEV
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CWE ID Description
CWE-401 The product does not sufficiently track and release allocated memory after it has been used, making the memory unavailable for reallocation and reuse.
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Executive Summary

This vulnerability exists in the Linux kernel's comedi driver. It involves a memory leak caused by improper handling of a command's runflags during an exceptional exit case in the function do_cmd_ioctl(). Specifically, when runflags is not set, the chanlist memory is not properly freed by the function do_become_nonbusy(), leading to a memory leak.

The issue arose because a commit that added reference counting for Comedi command handling did not consider the case where runflags was unset, causing the chanlist to remain allocated and not reclaimed.

The fix involved adding a check in do_become_nonbusy() to properly free the chanlist memory even when runflags is not set.

Impact Analysis

This vulnerability can lead to a memory leak in systems using the comedi driver in the Linux kernel. Over time, the unreclaimed memory could accumulate, potentially causing increased memory usage, degraded system performance, or even system instability or crashes if memory exhaustion occurs.

Detection Guidance

This vulnerability involves a memory leak in the Linux kernel's comedi driver due to improper freeing of chanlist memory when runflags is not set.

Detection would typically involve monitoring for memory leaks or unusual memory usage patterns related to the comedi driver.

Since no specific detection commands or tools are provided in the available information, general Linux memory debugging tools such as 'dmesg' to check kernel logs for BUG messages, or using tools like 'valgrind' or kernel memory leak detectors might help identify symptoms.

However, no explicit commands or detection methods are detailed in the provided data.

Mitigation Strategies

The vulnerability has been resolved by adding a check in the do_become_nonbusy() function to properly free the chanlist memory even when runflags is not set.

Immediate mitigation steps would include updating the Linux kernel to a version that contains the fix for this issue.

No other specific mitigation steps or workarounds are provided in the available information.

Compliance Impact

The provided information does not include any details about the impact of this vulnerability on compliance with common standards and regulations such as GDPR or HIPAA.

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