Bugzilla – Bug 1224828
VUL-0: CVE-2021-47225: kernel: mac80211: fix deadlock in AP/VLAN handling
Last modified: 2024-07-03 13:33:20 UTC
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 References: http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2021-47225 https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2021/CVE-2021-47225.mbox https://git.kernel.org/stable/c/8043903fcb72f545c52e3ec74d6fd82ef79ce7c5 https://git.kernel.org/stable/c/d5befb224edbe53056c2c18999d630dafb4a08b9 https://www.cve.org/CVERecord?id=CVE-2021-47225
All done, closing.