KASAN: slab-use-after-free Write in enqueue_timer (2)

Status: closed as invalid on 2026/04/08 13:13
Subsystems: wireguard
[Documentation on labels]
First crash: 201d, last: 170d
▶ ▼ Similar bugs (9)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KASAN: slab-use-after-free Write in enqueue_timer net 22 18 1183d 1198d 0/29 auto-obsoleted due to no activity on 2023/08/22 15:17
android-54 KASAN: use-after-free Write in enqueue_timer (2) 22 syz, C 5369 441d 539d 0/2 upstream: reported C repro on 2025/02/17 15:17
android-54 KASAN: use-after-free Write in enqueue_timer 22 syz, C 4288 768d 1275d 0/2 auto-obsoleted due to no activity on 2024/09/11 16:22
upstream KASAN: use-after-free Write in enqueue_timer net 22 1 1365d 1365d 22/29 fixed on 2023/02/24 13:50
android-5-15 KASAN: use-after-free Write in enqueue_timer 22 1 936d 936d 0/2 auto-obsoleted due to no activity on 2024/04/17 12:01
android-6-1 KASAN: use-after-free Write in enqueue_timer origin:lts 22 syz, C 684 4h08m 747d 0/2 upstream: reported C repro on 2024/07/25 13:16
upstream KASAN: slab-out-of-bounds Write in enqueue_timer bluetooth 21 1 419d 414d 0/29 auto-obsoleted due to no activity on 2025/09/26 09:41
upstream KASAN: invalid-access Write in enqueue_timer ext4 -1 20 1980d 2002d 0/29 auto-closed as invalid on 2021/07/08 00:48
android-5-15 KASAN: use-after-free Write in enqueue_timer (2) 22 2 215d 283d 0/2 auto-obsoleted due to no activity on 2026/04/08 11:13

Sample crash report:
==================================================================
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+0xc3/0x5c0 kernel/time/timer.c:616
Write of size 8 at addr ffff888062279f40 by task ktimers/1/29

CPU: 1 UID: 0 PID: 29 Comm: ktimers/1 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
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+0xc3/0x5c0 kernel/time/timer.c:616
 __mod_timer+0xb55/0xf60 kernel/time/timer.c:-1
 addrconf_mod_rs_timer+0x51/0xe0 net/ipv6/addrconf.c:331
 addrconf_rs_timer+0x49f/0x6d0 net/ipv6/addrconf.c:4052
 call_timer_fn+0x192/0x640 kernel/time/timer.c:1748
 expire_timers kernel/time/timer.c:1799 [inline]
 __run_timers kernel/time/timer.c:2373 [inline]
 __run_timer_base+0x6a3/0x9f0 kernel/time/timer.c:2385
 run_timer_base kernel/time/timer.c:2394 [inline]
 run_timer_softirq+0xb7/0x170 kernel/time/timer.c:2404
 handle_softirqs+0x1de/0x6f0 kernel/softirq.c:622
 __do_softirq kernel/softirq.c:656 [inline]
 run_ktimerd+0x69/0x100 kernel/softirq.c:1138
 smpboot_thread_fn+0x541/0xa50 kernel/smpboot.c:160
 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 11140:
 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:4501 [inline]
 slab_alloc_node mm/slub.c:4830 [inline]
 kmem_cache_alloc_node_noprof+0x22a/0x6e0 mm/slub.c:4882
 kmalloc_reserve net/core/skbuff.c:613 [inline]
 __alloc_skb+0x27d/0x7d0 net/core/skbuff.c:713
 alloc_skb include/linux/skbuff.h:1383 [inline]
 alloc_uevent_skb+0x7d/0x230 lib/kobject_uevent.c:289
 uevent_net_broadcast_tagged lib/kobject_uevent.c:352 [inline]
 kobject_uevent_net_broadcast+0x184/0x560 lib/kobject_uevent.c:413
 kobject_uevent_env+0x55f/0x9e0 lib/kobject_uevent.c:608
 rx_queue_add_kobject net/core/net-sysfs.c:1280 [inline]
 net_rx_queue_update_kobjects+0x3e5/0x740 net/core/net-sysfs.c:1322
 register_queue_kobjects net/core/net-sysfs.c:2114 [inline]
 netdev_register_kobject+0x21f/0x310 net/core/net-sysfs.c:2362
 register_netdevice+0x12d7/0x1d10 net/core/dev.c:11412
 veth_newlink+0x67b/0xb70 drivers/net/veth.c:1889
 rtnl_newlink_create+0x329/0xb70 net/core/rtnetlink.c:3840
 __rtnl_newlink net/core/rtnetlink.c:3957 [inline]
 rtnl_newlink+0x1666/0x1be0 net/core/rtnetlink.c:4072
 rtnetlink_rcv_msg+0x7d5/0xbe0 net/core/rtnetlink.c:6958
 netlink_rcv_skb+0x232/0x4b0 net/netlink/af_netlink.c:2550
 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
 netlink_unicast+0x831/0x9f0 net/netlink/af_netlink.c:1344
 netlink_sendmsg+0x813/0xb40 net/netlink/af_netlink.c:1894
 sock_sendmsg_nosec net/socket.c:727 [inline]
 __sock_sendmsg net/socket.c:742 [inline]
 __sys_sendto+0x72a/0x7d0 net/socket.c:2206
 __do_sys_sendto net/socket.c:2213 [inline]
 __se_sys_sendto net/socket.c:2209 [inline]
 __x64_sys_sendto+0xde/0x100 net/socket.c:2209
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 11140:
 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:2687 [inline]
 slab_free mm/slub.c:6124 [inline]
 kmem_cache_free+0x185/0x6b0 mm/slub.c:6254
 skb_kfree_head net/core/skbuff.c:1087 [inline]
 skb_free_head net/core/skbuff.c:1101 [inline]
 skb_release_data+0x6c3/0x940 net/core/skbuff.c:1128
 skb_release_all net/core/skbuff.c:1203 [inline]
 __kfree_skb+0x5d/0x210 net/core/skbuff.c:1217
 netlink_broadcast_filtered+0xede/0x1010 net/netlink/af_netlink.c:1535
 netlink_broadcast+0x37/0x50 net/netlink/af_netlink.c:1557
 uevent_net_broadcast_tagged lib/kobject_uevent.c:373 [inline]
 kobject_uevent_net_broadcast+0x4bf/0x560 lib/kobject_uevent.c:413
 kobject_uevent_env+0x55f/0x9e0 lib/kobject_uevent.c:608
 rx_queue_add_kobject net/core/net-sysfs.c:1280 [inline]
 net_rx_queue_update_kobjects+0x3e5/0x740 net/core/net-sysfs.c:1322
 register_queue_kobjects net/core/net-sysfs.c:2114 [inline]
 netdev_register_kobject+0x21f/0x310 net/core/net-sysfs.c:2362
 register_netdevice+0x12d7/0x1d10 net/core/dev.c:11412
 veth_newlink+0x67b/0xb70 drivers/net/veth.c:1889
 rtnl_newlink_create+0x329/0xb70 net/core/rtnetlink.c:3840
 __rtnl_newlink net/core/rtnetlink.c:3957 [inline]
 rtnl_newlink+0x1666/0x1be0 net/core/rtnetlink.c:4072
 rtnetlink_rcv_msg+0x7d5/0xbe0 net/core/rtnetlink.c:6958
 netlink_rcv_skb+0x232/0x4b0 net/netlink/af_netlink.c:2550
 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
 netlink_unicast+0x831/0x9f0 net/netlink/af_netlink.c:1344
 netlink_sendmsg+0x813/0xb40 net/netlink/af_netlink.c:1894
 sock_sendmsg_nosec net/socket.c:727 [inline]
 __sock_sendmsg net/socket.c:742 [inline]
 __sys_sendto+0x72a/0x7d0 net/socket.c:2206
 __do_sys_sendto net/socket.c:2213 [inline]
 __se_sys_sendto net/socket.c:2209 [inline]
 __x64_sys_sendto+0xde/0x100 net/socket.c:2209
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff888062279d40
 which belongs to the cache skbuff_small_head of size 704
The buggy address is located 512 bytes inside of
 freed 704-byte region [ffff888062279d40, ffff88806227a000)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x62278
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 ffff88801d28fc80 dead000000000100 dead000000000122
raw: 0000000000000000 0000000000130013 00000000f5000000 0000000000000000
head: 0080000000000040 ffff88801d28fc80 dead000000000100 dead000000000122
head: 0000000000000000 0000000000130013 00000000f5000000 0000000000000000
head: 0080000000000002 ffffea0001889e01 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 5458, tgid 5458 (dhcpcd), ts 500979056200, free_ts 500923963707
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x231/0x280 mm/page_alloc.c:1889
 prep_new_page mm/page_alloc.c:1897 [inline]
 get_page_from_freelist+0x28bb/0x2950 mm/page_alloc.c:3962
 __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5250
 alloc_slab_page mm/slub.c:3255 [inline]
 allocate_slab+0x77/0x660 mm/slub.c:3444
 new_slab mm/slub.c:3502 [inline]
 refill_objects+0x334/0x3c0 mm/slub.c:7134
 refill_sheaf mm/slub.c:2804 [inline]
 __pcs_replace_empty_main+0x328/0x5f0 mm/slub.c:4578
 alloc_from_pcs mm/slub.c:4681 [inline]
 slab_alloc_node mm/slub.c:4815 [inline]
 kmem_cache_alloc_node_noprof+0x4f4/0x6e0 mm/slub.c:4882
 kmalloc_reserve net/core/skbuff.c:613 [inline]
 __alloc_skb+0x27d/0x7d0 net/core/skbuff.c:713
 netlink_sendmsg+0x5d4/0xb40 net/netlink/af_netlink.c:1869
 sock_sendmsg_nosec net/socket.c:727 [inline]
 __sock_sendmsg net/socket.c:742 [inline]
 ____sys_sendmsg+0xa4e/0xac0 net/socket.c:2592
 ___sys_sendmsg+0x2a5/0x360 net/socket.c:2646
 __sys_sendmsg net/socket.c:2678 [inline]
 __do_sys_sendmsg net/socket.c:2683 [inline]
 __se_sys_sendmsg net/socket.c:2681 [inline]
 __x64_sys_sendmsg+0x1c3/0x2a0 net/socket.c:2681
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
page last free pid 56 tgid 56 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 __free_pages_prepare mm/page_alloc.c:1433 [inline]
 __free_frozen_pages+0xfe3/0x1170 mm/page_alloc.c:2978
 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:11719
 ieee80211_unregister_hw+0x128/0x2c0 net/mac80211/main.c:1700
 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+0x56e/0x800 net/core/net_namespace.c:704
 process_one_work kernel/workqueue.c:3275 [inline]
 process_scheduled_works+0xb02/0x1830 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:
 ffff888062279e00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888062279e80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888062279f00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                           ^
 ffff888062279f80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88806227a000: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================

Crashes (4):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/02/22 11:31 upstream fa5c82f4d2bb 6e7b5511 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs KASAN: slab-use-after-free Write in enqueue_timer
2026/02/15 09:59 upstream c22e26bd0906 1e62d198 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root KASAN: slab-use-after-free Write in enqueue_timer
2026/01/21 16:03 upstream 6c790212c588 d1b870e1 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto KASAN: slab-use-after-free Write in enqueue_timer
2026/02/19 22:46 upstream 8bf22c33e7a1 c8d8c52d .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs KASAN: use-after-free Write in enqueue_timer
* Struck through repros no longer work on HEAD.