wifi: mac80211: fix fils_discovery double free on alloc failure

Summary

In the Linux kernel, the following vulnerability has been resolved: wifi: mac80211: fix fils_discovery double free on alloc failure ieee80211_set_fils_discovery() calls kfree_rcu() on the old template before allocating the replacement. If the kzalloc() then fails, it returns -ENOMEM while link->u.ap.fils_discovery still points at the object already queued for freeing. A later update or AP teardown (ieee80211_stop_ap()) re-queues that same rcu_head; the second free is caught by KASAN when the RCU sheaf is processed in softirq: BUG: KASAN: double-free in rcu_free_sheaf (mm/slub.c:5850) Free of addr ffff88800c065280 by task swapper/0/0 ... __rcu_free_sheaf_prepare (mm/slub.c:2634 mm/slub.c:2940) rcu_free_sheaf (mm/slub.c:5850) rcu_core (kernel/rcu/tree.c:2617 kernel/rcu/tree.c:2869) handle_softirqs (kernel/softirq.c:622) The buggy address belongs to the cache kmalloc-96 of size 96 Queue the old object for kfree_rcu() only after the new one is published, matching ieee80211_set_probe_resp() and ieee80211_set_s1g_short_beacon().

Timeline

1. Aug 5, 2026, 8:08 AM UTCCVE published
2. Oct 16, 2026, 3:43 PM UTCCISA SSVC assessment

   Exploitation: none · Automatable: no · Technical impact: total

3. Oct 19, 2026, 8:48 PM UTCRecord last updated

Affected versions

• Linux Linux

  From 3b1c256eb4aedfc71dd97d5951ccff824b41d628 · fixed in e2c55079155a953db669ca1986a985fa286bad95; From 3b1c256eb4aedfc71dd97d5951ccff824b41d628 · fixed in 5baaa1042f71dd4b8e418f2cdd516808702d229b; From 3b1c256eb4aedfc71dd97d5951ccff824b41d628 · fixed in 1981fba71797ec95e6755fb882cad88899a2a84f; From 3b1c256eb4aedfc71dd97d5951ccff824b41d628 · fixed in 286e52a799fa158bdbd77da1426c4d93f9a6e7ad

• Linux Linux

  6.7

• KernelLinux

  From 6.7.0 · fixed in 6.12.101; From 6.13.0 · fixed in 6.18.42; From 6.19.0 · fixed in 7.1.6

References 4