CVE-2021-47477: comedi: dt9812: fix DMA buffers on stack

Severity: high (CVSS 7.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.7% 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: dt9812: fix DMA buffers on stack USB transfer buffers are typically mapped for DMA and must not be allocated on the stack or transfers will fail. Allocate proper transfer buffers in the various command helpers and return an error on short transfers instead of acting on random stack data. Note that this also fixes a stack info leak on systems where DMA is not used as 32 bytes are always sent to the device regardless of how short the command is.

Affected products

Linux kernel: from 2.6.29 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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