CVE-2021-47225

Summary

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

Affected Software

VendorProductVersion RangeStatus
LinuxLinuxa05829a7222e9d10c416dd2dbbf3929fe6646b89 < 8043903fcb72f545c52e3ec74d6fd82ef79ce7c5affected
LinuxLinuxa05829a7222e9d10c416dd2dbbf3929fe6646b89 < d5befb224edbe53056c2c18999d630dafb4a08b9affected
LinuxLinux5.12affected
LinuxLinux0 < 5.12unaffected
LinuxLinux5.12.13 <= 5.12.*unaffected
LinuxLinux5.13 <= *unaffected

Weaknesses

ADP Enrichment

CISA ADP Vulnrichment

  • SSVC:
  • Exploitation: none
    • Automatable: no
    • Technical Impact: partial

CVE Program Container

Additional References

References