CVE-2021-47231: can: mcba_usb: fix memory leak in mcba_usb

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: 2024-05-21 · updated 2026-06-17
Weakness: CWE-401

Description

In the Linux kernel, the following vulnerability has been resolved: can: mcba_usb: fix memory leak in mcba_usb Syzbot reported memory leak in SocketCAN driver for Microchip CAN BUS Analyzer Tool. The problem was in unfreed usb_coherent. In mcba_usb_start() 20 coherent buffers are allocated and there is nothing, that frees them: 1) In callback function the urb is resubmitted and that's all 2) In disconnect function urbs are simply killed, but URB_FREE_BUFFER is not set (see mcba_usb_start) and this flag cannot be used with coherent buffers. Fail log: | [ 1354.053291][ T8413] mcba_usb 1-1:0.0 can0: device disconnected | [ 1367.059384][ T8420] kmemleak: 20 new suspected memory leaks (see /sys/kernel/debug/kmem) So, all allocated buffers should be freed with usb_free_coherent() explicitly NOTE: The same pattern for allocating and freeing coherent buffers is used in drivers/net/can/usb/kvaser_usb/kvaser_usb_core.c

Affected products

Linux kernel: from 4.12 before 4.14.238; from 4.15 before 4.19.196; from 4.20 before 5.4.128; from 5.5 before 5.10.46; from 5.11 before 5.12.13; 5.13-rc1, 5.13-rc2, 5.13-rc3, 5.13-rc4, 5.13-rc5, 5.13-rc6 — fixed in 4.14.238, 4.19.196, 5.10.46, 5.12.13, 5.4.128

How to fix

Upgrade to a fixed version: Linux kernel 4.14.238, 4.19.196, 5.10.46, 5.12.13. Check the vendor advisory for mitigations.

References

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