published October 6, 2026
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.