==================================================================
BUG: KASAN: slab-use-after-free in hlist_add_head include/linux/list.h:1038 [inline]
BUG: KASAN: slab-use-after-free in enqueue_timer+0xc3/0x570 kernel/time/timer.c:616
Write of size 8 at addr ffff888063a39f40 by task kworker/1:8/5966

CPU: 1 UID: 0 PID: 5966 Comm: kworker/1:8 Tainted: G             L      syzkaller #0 PREEMPT_{RT,(full)} 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
Workqueue: wg-crypt-wg1 wg_packet_tx_worker
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xba/0x230 mm/kasan/report.c:482
 kasan_report+0x117/0x150 mm/kasan/report.c:595
 hlist_add_head include/linux/list.h:1038 [inline]
 enqueue_timer+0xc3/0x570 kernel/time/timer.c:616
 __mod_timer+0xb55/0xf60 kernel/time/timer.c:-1
 mod_peer_timer drivers/net/wireguard/timers.c:37 [inline]
 wg_timers_any_authenticated_packet_traversal+0x1fc/0x2f0 drivers/net/wireguard/timers.c:218
 wg_packet_create_data_done drivers/net/wireguard/send.c:247 [inline]
 wg_packet_tx_worker+0x16b/0x7c0 drivers/net/wireguard/send.c:276
 process_one_work kernel/workqueue.c:3275 [inline]
 process_scheduled_works+0xaec/0x17a0 kernel/workqueue.c:3358
 worker_thread+0xa50/0xfc0 kernel/workqueue.c:3439
 kthread+0x388/0x470 kernel/kthread.c:467
 ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>

Allocated by task 5029:
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 unpoison_slab_object mm/kasan/common.c:340 [inline]
 __kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:366
 kasan_slab_alloc include/linux/kasan.h:253 [inline]
 slab_post_alloc_hook mm/slub.c:4459 [inline]
 slab_alloc_node mm/slub.c:4788 [inline]
 kmem_cache_alloc_node_noprof+0x22a/0x6e0 mm/slub.c:4840
 kmalloc_reserve+0xbd/0x290 net/core/skbuff.c:586
 __alloc_skb+0x204/0x390 net/core/skbuff.c:690
 alloc_skb include/linux/skbuff.h:1383 [inline]
 nlmsg_new include/net/netlink.h:1055 [inline]
 inet6_ifmcaddr_notify+0xfa/0x1e0 net/ipv6/mcast.c:909
 __ipv6_dev_mc_dec+0x2dc/0x330 net/ipv6/mcast.c:1002
 addrconf_leave_solict net/ipv6/addrconf.c:2257 [inline]
 __ipv6_ifa_notify+0x77c/0xc60 net/ipv6/addrconf.c:6299
 addrconf_ifdown+0xff1/0x1aa0 net/ipv6/addrconf.c:3977
 addrconf_notify+0x1bc/0x1050 net/ipv6/addrconf.c:-1
 notifier_call_chain+0x19d/0x3a0 kernel/notifier.c:85
 call_netdevice_notifiers_extack net/core/dev.c:2281 [inline]
 call_netdevice_notifiers net/core/dev.c:2295 [inline]
 netif_close_many+0x2ae/0x420 net/core/dev.c:1798
 unregister_netdevice_many_notify+0xb47/0x2360 net/core/dev.c:12366
 unregister_netdevice_many net/core/dev.c:12459 [inline]
 default_device_exit_batch+0x981/0xa00 net/core/dev.c:13051
 ops_exit_list net/core/net_namespace.c:205 [inline]
 ops_undo_list+0x52b/0x940 net/core/net_namespace.c:252
 cleanup_net+0x4e5/0x7b0 net/core/net_namespace.c:696
 process_one_work kernel/workqueue.c:3275 [inline]
 process_scheduled_works+0xaec/0x17a0 kernel/workqueue.c:3358
 worker_thread+0xa50/0xfc0 kernel/workqueue.c:3439
 kthread+0x388/0x470 kernel/kthread.c:467
 ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Freed by task 5029:
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:584
 poison_slab_object mm/kasan/common.c:253 [inline]
 __kasan_slab_free+0x5c/0x80 mm/kasan/common.c:285
 kasan_slab_free include/linux/kasan.h:235 [inline]
 slab_free_hook mm/slub.c:2670 [inline]
 slab_free mm/slub.c:6082 [inline]
 kmem_cache_free+0x185/0x690 mm/slub.c:6212
 skb_kfree_head net/core/skbuff.c:1066 [inline]
 skb_free_head net/core/skbuff.c:1080 [inline]
 skb_release_data+0x688/0x8e0 net/core/skbuff.c:1107
 skb_release_all net/core/skbuff.c:1182 [inline]
 __kfree_skb+0x5d/0x210 net/core/skbuff.c:1196
 netlink_broadcast_filtered+0xede/0x1010 net/netlink/af_netlink.c:1535
 nlmsg_multicast_filtered include/net/netlink.h:1165 [inline]
 nlmsg_multicast include/net/netlink.h:1184 [inline]
 nlmsg_notify+0xf0/0x1a0 net/netlink/af_netlink.c:2593
 inet6_ifmcaddr_notify+0x143/0x1e0 net/ipv6/mcast.c:923
 __ipv6_dev_mc_dec+0x2dc/0x330 net/ipv6/mcast.c:1002
 addrconf_leave_solict net/ipv6/addrconf.c:2257 [inline]
 __ipv6_ifa_notify+0x77c/0xc60 net/ipv6/addrconf.c:6299
 addrconf_ifdown+0xff1/0x1aa0 net/ipv6/addrconf.c:3977
 addrconf_notify+0x1bc/0x1050 net/ipv6/addrconf.c:-1
 notifier_call_chain+0x19d/0x3a0 kernel/notifier.c:85
 call_netdevice_notifiers_extack net/core/dev.c:2281 [inline]
 call_netdevice_notifiers net/core/dev.c:2295 [inline]
 netif_close_many+0x2ae/0x420 net/core/dev.c:1798
 unregister_netdevice_many_notify+0xb47/0x2360 net/core/dev.c:12366
 unregister_netdevice_many net/core/dev.c:12459 [inline]
 default_device_exit_batch+0x981/0xa00 net/core/dev.c:13051
 ops_exit_list net/core/net_namespace.c:205 [inline]
 ops_undo_list+0x52b/0x940 net/core/net_namespace.c:252
 cleanup_net+0x4e5/0x7b0 net/core/net_namespace.c:696
 process_one_work kernel/workqueue.c:3275 [inline]
 process_scheduled_works+0xaec/0x17a0 kernel/workqueue.c:3358
 worker_thread+0xa50/0xfc0 kernel/workqueue.c:3439
 kthread+0x388/0x470 kernel/kthread.c:467
 ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

The buggy address belongs to the object at ffff888063a39d40
 which belongs to the cache skbuff_small_head of size 704
The buggy address is located 512 bytes inside of
 freed 704-byte region [ffff888063a39d40, ffff888063a3a000)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x63a38
head: order:2 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0x80000000000040(head|node=0|zone=1)
page_type: f5(slab)
raw: 0080000000000040 ffff88801debcb40 dead000000000122 0000000000000000
raw: 0000000000000000 0000000000130013 00000000f5000000 0000000000000000
head: 0080000000000040 ffff88801debcb40 dead000000000122 0000000000000000
head: 0000000000000000 0000000000130013 00000000f5000000 0000000000000000
head: 0080000000000002 ffffea00018e8e01 00000000ffffffff 00000000ffffffff
head: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000004
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 2, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 5029, tgid 5029 (kworker/u8:13), ts 282415784678, free_ts 276647038484
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x228/0x280 mm/page_alloc.c:1884
 prep_new_page mm/page_alloc.c:1892 [inline]
 get_page_from_freelist+0x28bb/0x2950 mm/page_alloc.c:3950
 __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5245
 alloc_slab_page mm/slub.c:3238 [inline]
 allocate_slab+0x77/0x660 mm/slub.c:3411
 new_slab mm/slub.c:3469 [inline]
 refill_objects+0x334/0x3c0 mm/slub.c:7091
 refill_sheaf mm/slub.c:2787 [inline]
 __pcs_replace_empty_main+0x328/0x5f0 mm/slub.c:4536
 alloc_from_pcs mm/slub.c:4639 [inline]
 slab_alloc_node mm/slub.c:4773 [inline]
 kmem_cache_alloc_node_noprof+0x4f4/0x6e0 mm/slub.c:4840
 kmalloc_reserve+0xbd/0x290 net/core/skbuff.c:586
 __alloc_skb+0x204/0x390 net/core/skbuff.c:690
 alloc_skb include/linux/skbuff.h:1383 [inline]
 nlmsg_new include/net/netlink.h:1055 [inline]
 inet6_ifmcaddr_notify+0xfa/0x1e0 net/ipv6/mcast.c:909
 __ipv6_dev_mc_dec+0x2dc/0x330 net/ipv6/mcast.c:1002
 addrconf_leave_solict net/ipv6/addrconf.c:2257 [inline]
 __ipv6_ifa_notify+0x77c/0xc60 net/ipv6/addrconf.c:6299
 addrconf_ifdown+0xff1/0x1aa0 net/ipv6/addrconf.c:3977
 addrconf_notify+0x1bc/0x1050 net/ipv6/addrconf.c:-1
 notifier_call_chain+0x19d/0x3a0 kernel/notifier.c:85
 call_netdevice_notifiers_extack net/core/dev.c:2281 [inline]
 call_netdevice_notifiers net/core/dev.c:2295 [inline]
 netif_close_many+0x2ae/0x420 net/core/dev.c:1798
page last free pid 5029 tgid 5029 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1433 [inline]
 __free_frozen_pages+0xfd0/0x1160 mm/page_alloc.c:2973
 device_release+0x9e/0x1d0 drivers/base/core.c:-1
 kobject_cleanup lib/kobject.c:689 [inline]
 kobject_release lib/kobject.c:720 [inline]
 kref_put include/linux/kref.h:65 [inline]
 kobject_put+0x228/0x560 lib/kobject.c:737
 netdev_run_todo+0xc75/0xde0 net/core/dev.c:11713
 ieee80211_unregister_hw+0x128/0x2c0 net/mac80211/main.c:1690
 mac80211_hwsim_del_radio+0x28a/0x490 drivers/net/wireless/virtual/mac80211_hwsim.c:5916
 hwsim_exit_net+0xf02/0xfc0 drivers/net/wireless/virtual/mac80211_hwsim.c:6807
 ops_exit_list net/core/net_namespace.c:199 [inline]
 ops_undo_list+0x49f/0x940 net/core/net_namespace.c:252
 cleanup_net+0x4e5/0x7b0 net/core/net_namespace.c:696
 process_one_work kernel/workqueue.c:3275 [inline]
 process_scheduled_works+0xaec/0x17a0 kernel/workqueue.c:3358
 worker_thread+0xa50/0xfc0 kernel/workqueue.c:3439
 kthread+0x388/0x470 kernel/kthread.c:467
 ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Memory state around the buggy address:
 ffff888063a39e00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888063a39e80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888063a39f00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                           ^
 ffff888063a39f80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888063a3a000: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================