CVE-2025-38481: comedi: Fail COMEDI_INSNLIST ioctl if n_insns is too large

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2025-07-28 · updated 2026-06-17

Description

In the Linux kernel, the following vulnerability has been resolved: comedi: Fail COMEDI_INSNLIST ioctl if n_insns is too large The handling of the `COMEDI_INSNLIST` ioctl allocates a kernel buffer to hold the array of `struct comedi_insn`, getting the length from the `n_insns` member of the `struct comedi_insnlist` supplied by the user. The allocation will fail with a WARNING and a stack dump if it is too large. Avoid that by failing with an `-EINVAL` error if the supplied `n_insns` value is unreasonable. Define the limit on the `n_insns` value in the `MAX_INSNS` macro. Set this to the same value as `MAX_SAMPLES` (65536), which is the maximum allowed sum of the values of the member `n` in the array of `struct comedi_insn`, and sensible comedi instructions will have an `n` of at least 1.

Affected products

Debian Linux: 11.0
Linux kernel: from 2.6.29 before 5.4.297; from 5.5 before 5.10.241; from 5.11 before 5.15.190; from 5.16 before 6.1.147; from 6.2 before 6.6.100; from 6.7 before 6.12.40 — fixed in 5.10.241, 5.15.190, 5.4.297, 6.1.147, 6.12.40, 6.15.8

How to fix

Upgrade to a fixed version: Linux kernel 5.10.241, 5.15.190, 5.4.297, 6.1.147. Check the vendor advisory for mitigations.

References

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