In the Linux kernel, the following vulnerability has been resolved: wifi: mac80211: reset state when starting AP fails ieee80211_start_ap() can set enable_beacon (and beacon_int) and fail later, leaving it set forever

Overview

In the Linux kernel, the following vulnerability has been resolved:

wifi: mac80211: reset state when starting AP fails

ieee80211_start_ap() can set enable_beacon (and beacon_int) and fail later, leaving it set forever. Scanning can then attempt to restore beaconing on such an interface, leading to:

Oops: divide error: 0000 [#1] SMP KASAN NOPTI RIP: 0010:mac80211_hwsim_link_info_changed+0xca7/0xf00 Call Trace: drv_link_info_changed+0x413/0x860 net/mac80211/driver-ops.c:495 ieee80211_link_info_change_notify+0x24b/0x3c0 net/mac80211/main.c:427 ieee80211_offchannel_return+0x381/0x580 net/mac80211/offchannel.c:160 __ieee80211_scan_completed+0x993/0xe30 net/mac80211/scan.c:519 ieee80211_scan_work+0x472/0x2010 net/mac80211/scan.c:1193 cfg80211_wiphy_work+0x2b7/0x550 net/wireless/core.c:538

in hwsim. Also, cfg80211 then allows changing the interface type, and the off-channel path getgs confused about beaconing as well, leading to another warning:

WARNING: net/mac80211/driver-ops.c:468 at drv_link_info_changed+0x583/0x880 ieee80211_link_info_change_notify+0x24b/0x3c0 net/mac80211/main.c:427 ieee80211_offchannel_stop_vifs+0x328/0x5c0 net/mac80211/offchannel.c:122 ieee80211_start_sw_scan net/mac80211/scan.c:583 [inline] __ieee80211_start_scan+0xfb6/0x1af0 net/mac80211/scan.c:882

Reset the state on failures to always have it correct.

Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.