CVE-2021-47361: mcb: fix error handling in mcb_alloc_bus()

Severity: high (CVSS 7.8 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: 2024-05-21 · updated 2026-06-17
Weakness: CWE-416

Description

In the Linux kernel, the following vulnerability has been resolved: mcb: fix error handling in mcb_alloc_bus() There are two bugs: 1) If ida_simple_get() fails then this code calls put_device(carrier) but we haven't yet called get_device(carrier) and probably that leads to a use after free. 2) After device_initialize() then we need to use put_device() to release the bus. This will free the internal resources tied to the device and call mcb_free_bus() which will free the rest.

Affected products

Linux kernel: from 4.7 before 4.9.285; from 4.10 before 4.14.249; from 4.15 before 4.19.209; from 4.20 before 5.4.150; from 5.5 before 5.10.70; from 5.11 before 5.14.9 — fixed in 4.14.249, 4.19.209, 4.9.285, 5.10.70, 5.14.9, 5.4.150

How to fix

Upgrade to a fixed version: Linux kernel 4.14.249, 4.19.209, 4.9.285, 5.10.70. Check the vendor advisory for mitigations.

References

Get alerted when CVE-2021-47361 or the next vulnerability affects your stack