==================================================================
BUG: KASAN: use-after-free in rcu_cblist_dequeue+0x6c/0xb0 kernel/rcu/rcu_segcblist.c:75
Read of size 8 at addr ffff888117266190 by task syz.0.862/4254
CPU: 0 PID: 4254 Comm: syz.0.862 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/06/2026
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+0x3e2/0xaf0 kernel/rcu/tree.c:2483
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:check_kcov_mode kernel/kcov.c:156 [inline]
RIP: 0010:write_comp_data kernel/kcov.c:209 [inline]
RIP: 0010:__sanitizer_cov_trace_cmp8+0x30/0x80 kernel/kcov.c:255
Code: 45 08 65 48 8b 0d 40 b4 9d 7e 65 8b 15 45 b4 9d 7e f7 c2 00 01 ff 00 74 11 f7 c2 00 01 00 00 74 57 83 b9 dc 0a 00 00 00 74 4e <8b> 91 b8 0a 00 00 83 fa 03 75 43 48 8b 91 c0 0a 00 00 44 8b 89 bc
RSP: 0018:ffffc90000bd7cd0 EFLAGS: 00000246
RAX: ffffffff8155d357 RBX: 1ffff9200017afa0 RCX: ffff88811a572800
RDX: 0000000080000000 RSI: 00000000000f4240 RDI: 00000000000f4240
RBP: ffffc90000bd7cd0 R08: ffffc90000bd7d67 R09: ffffc90000bd7d20
R10: dffffc0000000000 R11: fffff5200017afad R12: 00000000000f4240
R13: 00000000000f4240 R14: 0000000000000001 R15: 0000000000000000
hrtimer_nanosleep+0x177/0x400 kernel/time/hrtimer.c:-1
common_nsleep+0x8f/0xb0 kernel/time/posix-timers.c:1268
__do_sys_clock_nanosleep kernel/time/posix-timers.c:1309 [inline]
__se_sys_clock_nanosleep+0x30b/0x3a0 kernel/time/posix-timers.c:1286
__x64_sys_clock_nanosleep+0x9b/0xb0 kernel/time/posix-timers.c:1286
do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x61/0xcb
RIP: 0033:0x7fb809144d0e
Code: 08 0f 85 a5 a8 ff ff 49 89 fb 48 89 f0 48 89 d7 48 89 ce 4c 89 c2 4d 89 ca 4c 8b 44 24 08 4c 8b 4c 24 10 4c 89 5c 24 08 0f 05 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 80 00 00 00 00 48 83 ec 08
RSP: 002b:00007ffcd2508898 EFLAGS: 00000246 ORIG_RAX: 00000000000000e6
RAX: ffffffffffffffda RBX: 00005555824d2500 RCX: 00007fb809144d0e
RDX: 00007ffcd25088f0 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007fb809402da0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000002df7f
R13: 00007fb80940109c R14: 000000000002dd68 R15: 00007fb809401090
Allocated by task 4269:
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 9:
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:175
exit_to_user_mode_prepare+0x76/0xa0 kernel/entry/common.c:202
syscall_exit_to_user_mode+0x1d/0x40 kernel/entry/common.c:277
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
addrconf_sysctl_unregister net/ipv6/addrconf.c:7146 [inline]
addrconf_ifdown+0x1628/0x1890 net/ipv6/addrconf.c:3954
addrconf_notify+0x3bd/0xea0 net/ipv6/addrconf.c:-1
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:10779
default_device_exit_batch+0x35e/0x3c0 net/core/dev.c:11299
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 ffff888117266000
which belongs to the cache kmalloc-512 of size 512
The buggy address is located 400 bytes inside of
512-byte region [ffff888117266000, ffff888117266200)
The buggy address belongs to the page:
page:ffffea00045c9900 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x117264
head:ffffea00045c9900 order:2 compound_mapcount:0 compound_pincount:0
flags: 0x4000000000010200(slab|head)
raw: 4000000000010200 ffffea00045b2d00 0000000300000003 ffff888100043080
raw: 0000000000000000 0000000000100010 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 0x1d2a20(GFP_ATOMIC|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_HARDWALL), pid 0, ts 53084367294, free_ts 52839399809
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]
ndisc_alloc_skb net/ipv6/ndisc.c:422 [inline]
ndisc_send_rs+0x310/0x960 net/ipv6/ndisc.c:691
addrconf_rs_timer+0x35a/0x600 net/ipv6/addrconf.c:3982
call_timer_fn+0x38/0x290 kernel/time/timer.c:1450
expire_timers kernel/time/timer.c:1495 [inline]
__run_timers+0x637/0x9a0 kernel/time/timer.c:1789
run_timer_softirq+0x6a/0xf0 kernel/time/timer.c:1802
__do_softirq+0x255/0x563 kernel/softirq.c:309
page last free stack trace:
reset_page_owner include/linux/page_owner.h:28 [inline]
free_pages_prepare mm/page_alloc.c:1349 [inline]
free_pcp_prepare mm/page_alloc.c:1421 [inline]
free_unref_page_prepare+0x2b7/0x2d0 mm/page_alloc.c:3336
free_unref_page mm/page_alloc.c:3391 [inline]
free_the_page mm/page_alloc.c:5443 [inline]
__free_pages+0x146/0x390 mm/page_alloc.c:5454
__vunmap+0x801/0x980 mm/vmalloc.c:2307
__vfree mm/vmalloc.c:2356 [inline]
vfree+0x61/0x90 mm/vmalloc.c:2387
htable_put+0x5fb/0x650 net/netfilter/xt_hashlimit.c:434
hashlimit_mt_destroy+0x5c/0x70 net/netfilter/xt_hashlimit.c:991
cleanup_match net/ipv6/netfilter/ip6_tables.c:479 [inline]
cleanup_entry+0x156/0x350 net/ipv6/netfilter/ip6_tables.c:668
translate_table+0x1ee3/0x20d0 net/ipv6/netfilter/ip6_tables.c:751
do_replace net/ipv6/netfilter/ip6_tables.c:1159 [inline]
do_ip6t_set_ctl+0x960/0xd80 net/ipv6/netfilter/ip6_tables.c:1648
nf_setsockopt+0x272/0x2a0 net/netfilter/nf_sockopt.c:101
ipv6_setsockopt+0x2568/0x36f0 net/ipv6/ipv6_sockglue.c:1014
rawv6_setsockopt+0x29e/0x660 net/ipv6/raw.c:1057
sock_common_setsockopt+0xa0/0xb0 net/core/sock.c:3333
__sys_setsockopt+0x2fa/0x480 net/socket.c:2147
__do_sys_setsockopt net/socket.c:2158 [inline]
__se_sys_setsockopt net/socket.c:2155 [inline]
__x64_sys_setsockopt+0xbf/0xd0 net/socket.c:2155
do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46
Memory state around the buggy address:
ffff888117266080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888117266100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888117266180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff888117266200: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff888117266280: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================
----------------
Code disassembly (best guess):
0: 45 08 65 48 or %r12b,0x48(%r13)
4: 8b 0d 40 b4 9d 7e mov 0x7e9db440(%rip),%ecx # 0x7e9db44a
a: 65 8b 15 45 b4 9d 7e mov %gs:0x7e9db445(%rip),%edx # 0x7e9db456
11: f7 c2 00 01 ff 00 test $0xff0100,%edx
17: 74 11 je 0x2a
19: f7 c2 00 01 00 00 test $0x100,%edx
1f: 74 57 je 0x78
21: 83 b9 dc 0a 00 00 00 cmpl $0x0,0xadc(%rcx)
28: 74 4e je 0x78
* 2a: 8b 91 b8 0a 00 00 mov 0xab8(%rcx),%edx <-- trapping instruction
30: 83 fa 03 cmp $0x3,%edx
33: 75 43 jne 0x78
35: 48 8b 91 c0 0a 00 00 mov 0xac0(%rcx),%rdx
3c: 44 rex.R
3d: 8b .byte 0x8b
3e: 89 .byte 0x89
3f: bc .byte 0xbc