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 theres no contention on the lock in any case. This trivially fixes the bug since we hold one wdevs lock already, and now will hold the lock that protects all lists.

Weakness

The product does not properly acquire or release a lock on a resource, leading to unexpected resource state changes and behaviors.

Affected Software

Extended Description

Locking is a type of synchronization behavior that ensures that multiple independently-operating processes or threads do not interfere with each other when accessing the same resource. All processes/threads are expected to follow the same steps for locking. If these steps are not followed precisely - or if no locking is done at all - then another process/thread could modify the shared resource in a way that is not visible or predictable to the original process. This can lead to data or memory corruption, denial of service, etc.

Potential Mitigations

Related Attack Patterns

• https://cwe.mitre.org/data/definitions/25.html
• https://cwe.mitre.org/data/definitions/26.html
• https://cwe.mitre.org/data/definitions/27.html

References

• 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