CVE-2021-47494: linux kernel — Fix

Description

In the Linux kernel, the following vulnerability has been resolved: cfg80211: fix management registrations locking The management registrations locking was broken, the list was locked for each wdev, but cfg80211_mgmt_registrations_update() iterated it without holding all the correct spinlocks, causing list corruption. Rather than trying to fix it with fine-grained locking, just move the lock to the wiphy/rdev (still need the list on each wdev), we already need to hold the wdev lock to change it, so there's no contention on the lock in any case. This trivially fixes the bug since we hold one wdev's lock already, and now will hold the lock that protects all lists.

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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-667 CWE-667

Affected Products

Vendor	Product	Versions
linux	linux_kernel	5.8 — 5.10.77
linux	linux_kernel	5.11 — 5.14.16
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All

References

Advisories & Patches

https://git.kernel.org/stable/c/09b1d5dc6ce1c9151777f6c4e128a59457704c97 https://git.kernel.org/stable/c/3c897f39b71fe68f90599f6a45b5f7bf5618420e https://git.kernel.org/stable/c/4c22227e39c7a0b4dab55617ee8d34d171fab8d4 https://git.kernel.org/stable/c/09b1d5dc6ce1c9151777f6c4e128a59457704c97 https://git.kernel.org/stable/c/3c897f39b71fe68f90599f6a45b5f7bf5618420e https://git.kernel.org/stable/c/4c22227e39c7a0b4dab55617ee8d34d171fab8d4

Frequently Asked Questions

What is CVE-2021-47494? +

In the Linux kernel, the following vulnerability has been resolved: cfg80211: fix management registrations locking The management registrations locking was broken, the list was locked for each wdev, but cfg80211_mgmt_registrations_update() iterated it without holding all the correct spinlocks, causing list corruption. Rather than trying to fix it with fine-grained locking, just move the lock to the wiphy/rdev (still need the list on each wdev), we already need to hold the wdev lock to change it, so there's no contention on the lock in any case. This trivially fixes the bug since we hold one wdev's lock already, and now will hold the lock that protects all lists. It has a CVSS v3.1 base score of 5.5 (MEDIUM).

How severe is CVE-2021-47494? +

CVE-2021-47494 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-2021-47494? +

CVE-2021-47494 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-2021-47494? +

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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CVE-2021-47494