Linux Kernel up to 5.12.12 mac80211 dev_close deadlock

Summaryinfo

A vulnerability categorized as critical has been discovered in Linux Kernel up to 5.12.12. The affected element is the function dev_close of the component mac80211. The manipulation results in deadlock. This vulnerability is reported as CVE-2021-47225. No exploit exists. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability classified as critical has been found in Linux Kernel up to 5.12.12. Affected is the function dev_close of the component mac80211. The manipulation with an unknown input leads to a deadlock vulnerability. CWE is classifying the issue as CWE-833. The product contains multiple threads or executable segments that are waiting for each other to release a necessary lock, resulting in deadlock. This is going to have an impact on availability. CVE summarizes:

In the Linux kernel, the following vulnerability has been resolved: mac80211: fix deadlock in AP/VLAN handling Syzbot reports that when you have AP_VLAN interfaces that are up and close the AP interface they belong to, we get a deadlock. No surprise - since we dev_close() them with the wiphy mutex held, which goes back into the netdev notifier in cfg80211 and tries to acquire the wiphy mutex there. To fix this, we need to do two things: 1) prevent changing iftype while AP_VLANs are up, we can't easily fix this case since cfg80211 already calls us with the wiphy mutex held, but change_interface() is relatively rare in drivers anyway, so changing iftype isn't used much (and userspace has to fall back to down/change/up anyway) 2) pull the dev_close() loop over VLANs out of the wiphy mutex section in the normal stop case

The advisory is shared for download at git.kernel.org. This vulnerability is traded as CVE-2021-47225 since 04/10/2024. There are known technical details, but no exploit is available.

Upgrading to version 5.12.13 eliminates this vulnerability. Applying the patch 8043903fcb72/d5befb224edb is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.

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Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 5.12.0
• 5.12.1
• 5.12.2
• 5.12.3
• 5.12.4
• 5.12.5
• 5.12.6
• 5.12.7
• 5.12.8
• 5.12.9
• 5.12.10
• 5.12.11
• 5.12.12

License

• open-source

Website

• Vendor: https://www.kernel.org/

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