CVE-2021-47475: comedi: vmk80xx: fix transfer-buffer overflows

Severity: high (CVSS 7.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2024-05-22 · updated 2026-06-17
Weakness: CWE-787

Description

In the Linux kernel, the following vulnerability has been resolved: comedi: vmk80xx: fix transfer-buffer overflows The driver uses endpoint-sized USB transfer buffers but up until recently had no sanity checks on the sizes. Commit e1f13c879a7c ("staging: comedi: check validity of wMaxPacketSize of usb endpoints found") inadvertently fixed NULL-pointer dereferences when accessing the transfer buffers in case a malicious device has a zero wMaxPacketSize. Make sure to allocate buffers large enough to handle also the other accesses that are done without a size check (e.g. byte 18 in vmk80xx_cnt_insn_read() for the VMK8061_MODEL) to avoid writing beyond the buffers, for example, when doing descriptor fuzzing. The original driver was for a low-speed device with 8-byte buffers. Support was later added for a device that uses bulk transfers and is presumably a full-speed device with a maximum 64-byte wMaxPacketSize.

Affected products

Linux kernel: from 2.6.31 before 4.4.292; from 4.5 before 4.9.290; from 4.10 before 4.14.255; from 4.15 before 4.19.217; from 4.20 before 5.4.159; from 5.5 before 5.10.79 — fixed in 4.14.255, 4.19.217, 4.4.292, 4.9.290, 5.10.79, 5.14.18

How to fix

Upgrade to a fixed version: Linux kernel 4.14.255, 4.19.217, 4.4.292, 4.9.290. Check the vendor advisory for mitigations.

References

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