CVE-2021-47231

MEDIUM
Published May 21, 2024 Modified Apr 4, 2025 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

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CVSS v3.1 Score

5.5
MEDIUM
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Weakness Type (CWE)

CWE-401 CWE-401

Affected Products

Vendor Product
linux linux_kernel
linux linux_kernel
linux linux_kernel
linux linux_kernel
linux linux_kernel
linux linux_kernel
linux linux_kernel
linux linux_kernel
linux linux_kernel
linux linux_kernel
linux linux_kernel

References

Advisories & Patches

https://git.kernel.org/stable/c/6bd3d80d1f019cefa7011056c54b323f1d8b8e83 https://git.kernel.org/stable/c/6f87c0e21ad20dd3d22108e33db1c552dfa352a0 https://git.kernel.org/stable/c/89df95ce32be204eef2e7d4b2f6fb552fb191a68 https://git.kernel.org/stable/c/91c02557174be7f72e46ed7311e3bea1939840b0 https://git.kernel.org/stable/c/a115198caaab6d663bef75823a3c5f0802306d60 https://git.kernel.org/stable/c/d0760a4ef85697bc756d06eae17ae27f3f055401 https://git.kernel.org/stable/c/6bd3d80d1f019cefa7011056c54b323f1d8b8e83 https://git.kernel.org/stable/c/6f87c0e21ad20dd3d22108e33db1c552dfa352a0 https://git.kernel.org/stable/c/89df95ce32be204eef2e7d4b2f6fb552fb191a68 https://git.kernel.org/stable/c/91c02557174be7f72e46ed7311e3bea1939840b0 https://git.kernel.org/stable/c/a115198caaab6d663bef75823a3c5f0802306d60 https://git.kernel.org/stable/c/d0760a4ef85697bc756d06eae17ae27f3f055401

Frequently Asked Questions

What is CVE-2021-47231? +
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 It has a CVSS v3.1 base score of 5.5 (MEDIUM).
How severe is CVE-2021-47231? +
CVE-2021-47231 has a CVSS v3.1 score of 5.5 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance.
What products are affected by CVE-2021-47231? +
CVE-2021-47231 affects products from linux, specifically: linux_kernel. Check the affected products table above for specific version ranges.
How do I check if I'm vulnerable to CVE-2021-47231? +
You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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