==================================================================
BUG: KASAN: use-after-free in rcu_cblist_dequeue+0x6c/0xb0 kernel/rcu/rcu_segcblist.c:75
Read of size 8 at addr ffff888127fca590 by task syz.3.3234/9423
CPU: 1 PID: 9423 Comm: syz.3.3234 Tainted: G W syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
__dump_stack+0x21/0x24 lib/dump_stack.c:77
dump_stack_lvl+0x1a7/0x208 lib/dump_stack.c:118
print_address_description+0x7f/0x2c0 mm/kasan/report.c:248
__kasan_report mm/kasan/report.c:435 [inline]
kasan_report+0x100/0x140 mm/kasan/report.c:452
__asan_report_load8_noabort+0x14/0x20 mm/kasan/report_generic.c:309
rcu_cblist_dequeue+0x6c/0xb0 kernel/rcu/rcu_segcblist.c:75
rcu_do_batch+0x448/0xaf0 kernel/rcu/tree.c:2484
rcu_core+0x50a/0xca0 kernel/rcu/tree.c:2735
rcu_core_si+0x9/0x10 kernel/rcu/tree.c:2748
__do_softirq+0x255/0x563 kernel/softirq.c:309
asm_call_irq_on_stack+0xf/0x20
__run_on_irqstack arch/x86/include/asm/irq_stack.h:26 [inline]
run_on_irqstack_cond arch/x86/include/asm/irq_stack.h:77 [inline]
do_softirq_own_stack+0x60/0x80 arch/x86/kernel/irq_64.c:77
invoke_softirq kernel/softirq.c:405 [inline]
__irq_exit_rcu+0x128/0x150 kernel/softirq.c:435
irq_exit_rcu+0x9/0x10 kernel/softirq.c:447
sysvec_apic_timer_interrupt+0xbf/0xe0 arch/x86/kernel/apic/apic.c:1106
asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:635
RIP: 0010:__raw_spin_unlock_irq include/linux/spinlock_api_smp.h:169 [inline]
RIP: 0010:_raw_spin_unlock_irq+0x49/0x70 kernel/locking/spinlock.c:199
Code: 12 48 89 fb 48 c7 c7 b0 73 4c 86 e8 f1 5c 1d fd 48 89 df 48 83 3d 36 b8 ca 01 00 74 27 e8 83 18 ca fc 66 90 fb bf 01 00 00 00 82 14 c3 fc 65 8b 05 f7 b1 80 7b 85 c0 74 03 5b 5d c3 e8 e3 b1
RSP: 0018:ffffc900010a73f0 EFLAGS: 00000246
RAX: 0000000000000001 RBX: dffffc0000000000 RCX: dffffc0000000000
RDX: 0000000000000001 RSI: ffffffff85406140 RDI: 0000000000000001
RBP: ffffc900010a73f8 R08: ffff888129b993c7 R09: 1ffff11025373278
R10: dffffc0000000000 R11: ffffed1025373279 R12: ffff8881f7155fc0
R13: ffff888129b993ec R14: 0000000000000000 R15: ffff8881135d8000
finish_lock_switch kernel/sched/core.c:3786 [inline]
finish_task_switch+0x12e/0x5a0 kernel/sched/core.c:3886
context_switch kernel/sched/core.c:4051 [inline]
__schedule+0xc0b/0x13e0 kernel/sched/core.c:4806
preempt_schedule_common+0x9b/0xf0 kernel/sched/core.c:4965
preempt_schedule+0xbc/0xd0 kernel/sched/core.c:4990
preempt_schedule_thunk+0x16/0x18 arch/x86/entry/thunk_64.S:39
__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:161 [inline]
_raw_spin_unlock_irqrestore+0x74/0x80 kernel/locking/spinlock.c:191
spin_unlock_irqrestore include/linux/spinlock.h:410 [inline]
__wake_up_common_lock kernel/sched/wait.c:126 [inline]
__wake_up_sync_key+0x17b/0x2b0 kernel/sched/wait.c:194
unix_dgram_recvmsg+0x49d/0xd30 net/unix/af_unix.c:2180
____sys_recvmsg+0x2ca/0x5b0 net/socket.c:-1
___sys_recvmsg+0x213/0x5c0 net/socket.c:2638
do_recvmmsg+0x358/0x7a0 net/socket.c:2732
__sys_recvmmsg net/socket.c:2811 [inline]
__do_sys_recvmmsg net/socket.c:2834 [inline]
__se_sys_recvmmsg net/socket.c:2827 [inline]
__x64_sys_recvmmsg+0x195/0x250 net/socket.c:2827
do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x61/0xcb
RIP: 0033:0x7fc4bdee30d9
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fc4bc91b028 EFLAGS: 00000246 ORIG_RAX: 000000000000012b
RAX: ffffffffffffffda RBX: 00007fc4be16b090 RCX: 00007fc4bdee30d9
RDX: 0000000000010106 RSI: 00002000000000c0 RDI: 0000000000000003
RBP: 00007fc4bdf7a024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000002 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fc4be16b128 R14: 00007fc4be16b090 R15: 00007fff7f42b818
Allocated by task 9426:
kasan_save_stack mm/kasan/common.c:38 [inline]
kasan_set_track mm/kasan/common.c:45 [inline]
set_alloc_info mm/kasan/common.c:430 [inline]
____kasan_kmalloc mm/kasan/common.c:509 [inline]
__kasan_kmalloc+0xd4/0x100 mm/kasan/common.c:518
kasan_kmalloc include/linux/kasan.h:254 [inline]
__kmalloc+0x19f/0x330 mm/slub.c:4038
kmalloc include/linux/slab.h:560 [inline]
kzalloc include/linux/slab.h:667 [inline]
l2tp_session_create+0x39/0xb60 net/l2tp/l2tp_core.c:1616
pppol2tp_connect+0xbf5/0x1640 net/l2tp/l2tp_ppp.c:772
__sys_connect_file net/socket.c:1867 [inline]
__sys_connect+0x3ce/0x450 net/socket.c:1884
__do_sys_connect net/socket.c:1894 [inline]
__se_sys_connect net/socket.c:1891 [inline]
__x64_sys_connect+0x7a/0x90 net/socket.c:1891
do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x61/0xcb
Freed by task 1398:
kasan_save_stack mm/kasan/common.c:38 [inline]
kasan_set_track+0x4a/0x70 mm/kasan/common.c:45
kasan_set_free_info+0x23/0x40 mm/kasan/generic.c:370
____kasan_slab_free+0x125/0x160 mm/kasan/common.c:362
__kasan_slab_free+0x11/0x20 mm/kasan/common.c:370
kasan_slab_free include/linux/kasan.h:220 [inline]
slab_free_hook mm/slub.c:1600 [inline]
slab_free_freelist_hook+0xc5/0x190 mm/slub.c:1626
slab_free mm/slub.c:3208 [inline]
kfree+0xc0/0x270 mm/slub.c:4196
l2tp_session_free net/l2tp/l2tp_core.c:168 [inline]
l2tp_session_put+0xb2/0x1a0 net/l2tp/l2tp_core.c:193
l2tp_session_delete+0x3a9/0x4a0 net/l2tp/l2tp_core.c:1589
l2tp_tunnel_closeall net/l2tp/l2tp_core.c:1235 [inline]
l2tp_tunnel_del_work+0x180/0x3d0 net/l2tp/l2tp_core.c:1273
process_one_work+0x6fd/0xbc0 kernel/workqueue.c:2301
worker_thread+0xa8e/0x13c0 kernel/workqueue.c:2447
kthread+0x324/0x3b0 kernel/kthread.c:313
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298
Last potentially related work creation:
kasan_save_stack+0x3a/0x60 mm/kasan/common.c:38
__kasan_record_aux_stack+0xd2/0x100 mm/kasan/generic.c:348
kasan_record_aux_stack_noalloc+0xb/0x10 mm/kasan/generic.c:358
__call_rcu kernel/rcu/tree.c:2980 [inline]
call_rcu+0x11a/0x1090 kernel/rcu/tree.c:3054
pppol2tp_release+0x1e3/0x2b0 net/l2tp/l2tp_ppp.c:447
__sock_release net/socket.c:597 [inline]
sock_close+0xb8/0x200 net/socket.c:1287
__fput+0x2dc/0x730 fs/file_table.c:281
____fput+0x15/0x20 fs/file_table.c:314
task_work_run+0x127/0x190 kernel/task_work.c:189
tracehook_notify_resume include/linux/tracehook.h:188 [inline]
exit_to_user_mode_loop+0xcb/0xe0 kernel/entry/common.c:172
exit_to_user_mode_prepare+0x76/0xa0 kernel/entry/common.c:199
syscall_exit_to_user_mode+0x1d/0x40 kernel/entry/common.c:274
do_syscall_64+0x3d/0x40 arch/x86/entry/common.c:56
entry_SYSCALL_64_after_hwframe+0x61/0xcb
Second to last potentially related work creation:
kasan_save_stack+0x3a/0x60 mm/kasan/common.c:38
__kasan_record_aux_stack+0xd2/0x100 mm/kasan/generic.c:348
kasan_record_aux_stack_noalloc+0xb/0x10 mm/kasan/generic.c:358
kvfree_call_rcu+0x117/0x670 kernel/rcu/tree.c:3539
drop_sysctl_table+0x2f5/0x430 fs/proc/proc_sysctl.c:1684
drop_sysctl_table+0x2e4/0x430 fs/proc/proc_sysctl.c:1687
unregister_sysctl_table+0x75/0x120 fs/proc/proc_sysctl.c:1722
unregister_net_sysctl_table+0x15/0x20 net/sysctl_net.c:127
neigh_sysctl_unregister+0x78/0x90 net/core/neighbour.c:3732
devinet_sysctl_unregister net/ipv4/devinet.c:2650 [inline]
inetdev_destroy net/ipv4/devinet.c:326 [inline]
inetdev_event+0x7df/0x1010 net/ipv4/devinet.c:1612
notifier_call_chain kernel/notifier.c:83 [inline]
raw_notifier_call_chain+0x90/0x100 kernel/notifier.c:410
call_netdevice_notifiers_info net/core/dev.c:2052 [inline]
call_netdevice_notifiers_extack net/core/dev.c:2064 [inline]
call_netdevice_notifiers net/core/dev.c:2078 [inline]
unregister_netdevice_many+0x100e/0x19f0 net/core/dev.c:10778
default_device_exit_batch+0x35e/0x3c0 net/core/dev.c:11298
ops_exit_list net/core/net_namespace.c:190 [inline]
cleanup_net+0x5fe/0xb80 net/core/net_namespace.c:609
process_one_work+0x6fd/0xbc0 kernel/workqueue.c:2301
worker_thread+0xa8e/0x13c0 kernel/workqueue.c:2447
kthread+0x324/0x3b0 kernel/kthread.c:313
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298
The buggy address belongs to the object at ffff888127fca400
which belongs to the cache kmalloc-512 of size 512
The buggy address is located 400 bytes inside of
512-byte region [ffff888127fca400, ffff888127fca600)
The buggy address belongs to the page:
page:ffffea00049ff200 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff888127fc9400 pfn:0x127fc8
head:ffffea00049ff200 order:2 compound_mapcount:0 compound_pincount:0
flags: 0x4000000000010200(slab|head)
raw: 4000000000010200 ffffea00042be100 0000000300000003 ffff888100043080
raw: ffff888127fc9400 000000008010000e 00000001ffffffff 0000000000000000
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 281, ts 22955960191, free_ts 0
set_page_owner include/linux/page_owner.h:35 [inline]
post_alloc_hook mm/page_alloc.c:2456 [inline]
prep_new_page+0x176/0x190 mm/page_alloc.c:2462
get_page_from_freelist+0x225f/0x23f0 mm/page_alloc.c:4254
__alloc_pages_nodemask+0x29a/0x640 mm/page_alloc.c:5384
alloc_slab_page mm/slub.c:-1 [inline]
allocate_slab mm/slub.c:1813 [inline]
new_slab+0x84/0x3f0 mm/slub.c:1874
new_slab_objects mm/slub.c:2632 [inline]
___slab_alloc+0x2f8/0x4c0 mm/slub.c:2796
__slab_alloc+0x63/0xa0 mm/slub.c:2836
slab_alloc_node mm/slub.c:2918 [inline]
slab_alloc mm/slub.c:2960 [inline]
__kmalloc_track_caller+0x1e4/0x310 mm/slub.c:4541
__kmalloc_reserve net/core/skbuff.c:144 [inline]
__alloc_skb+0xdc/0x520 net/core/skbuff.c:212
alloc_skb include/linux/skbuff.h:1126 [inline]
nlmsg_new include/net/netlink.h:953 [inline]
inet6_netconf_notify_devconf+0xd6/0x190 net/ipv6/addrconf.c:579
__addrconf_sysctl_register+0x36e/0x3e0 net/ipv6/addrconf.c:7072
addrconf_sysctl_register+0x147/0x1a0 net/ipv6/addrconf.c:7109
ipv6_add_dev+0xbb2/0x10b0 net/ipv6/addrconf.c:450
addrconf_notify+0x582/0xea0 net/ipv6/addrconf.c:3570
notifier_call_chain kernel/notifier.c:83 [inline]
raw_notifier_call_chain+0x90/0x100 kernel/notifier.c:410
call_netdevice_notifiers_info net/core/dev.c:2052 [inline]
call_netdevice_notifiers_extack net/core/dev.c:2064 [inline]
call_netdevice_notifiers+0x119/0x190 net/core/dev.c:2078
register_netdevice+0x100a/0x13a0 net/core/dev.c:10098
page_owner free stack trace missing
Memory state around the buggy address:
ffff888127fca480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888127fca500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888127fca580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff888127fca600: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff888127fca680: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0)
----------------
Code disassembly (best guess):
0: 12 48 89 adc -0x77(%rax),%cl
3: fb sti
4: 48 c7 c7 b0 73 4c 86 mov $0xffffffff864c73b0,%rdi
b: e8 f1 5c 1d fd call 0xfd1d5d01
10: 48 89 df mov %rbx,%rdi
13: 48 83 3d 36 b8 ca 01 cmpq $0x0,0x1cab836(%rip) # 0x1cab851
1a: 00
1b: 74 27 je 0x44
1d: e8 83 18 ca fc call 0xfcca18a5
22: 66 90 xchg %ax,%ax
24: fb sti
25: bf 01 00 00 00 mov $0x1,%edi
* 2a: e8 82 14 c3 fc call 0xfcc314b1 <-- trapping instruction
2f: 65 8b 05 f7 b1 80 7b mov %gs:0x7b80b1f7(%rip),%eax # 0x7b80b22d
36: 85 c0 test %eax,%eax
38: 74 03 je 0x3d
3a: 5b pop %rbx
3b: 5d pop %rbp
3c: c3 ret
3d: e8 .byte 0xe8
3e: e3 b1 jrcxz 0xfffffff1