Overview
About vulnerability
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().
Details
- Affected product:
- AlmaLinux 9.2 ESU , Debian 10 ELS , TuxCare 9.6 ESU
- Affected packages:
- linux @ 4.19.0 (+2 more)
Fixes
KernelCare state
Live-patch status from KernelCare for each operating system.
| Operating system | Status | Covered kernels |
|---|---|---|
| Debian 13 | Planned | — |