==================================================================
BUG: KASAN: use-after-free in rcu_segcblist_restempty kernel/rcu/rcu_segcblist.h:112 [inline]
BUG: KASAN: use-after-free in rcu_segcblist_accelerate+0x1e7/0x420 kernel/rcu/rcu_segcblist.c:579
Read of size 8 at addr ffff8881321fa190 by task syz.3.1670/6071
CPU: 1 PID: 6071 Comm: syz.3.1670 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
Call Trace:
__dump_stack+0x21/0x24 lib/dump_stack.c:88
dump_stack_lvl+0x110/0x170 lib/dump_stack.c:106
print_address_description+0x71/0x200 mm/kasan/report.c:316
print_report+0x4a/0x60 mm/kasan/report.c:420
kasan_report+0x122/0x150 mm/kasan/report.c:524
__asan_report_load8_noabort+0x14/0x20 mm/kasan/report_generic.c:351
rcu_segcblist_restempty kernel/rcu/rcu_segcblist.h:112 [inline]
rcu_segcblist_accelerate+0x1e7/0x420 kernel/rcu/rcu_segcblist.c:579
rcu_accelerate_cbs kernel/rcu/tree.c:1150 [inline]
rcu_report_qs_rdp kernel/rcu/tree.c:2088 [inline]
rcu_check_quiescent_state kernel/rcu/tree.c:2141 [inline]
rcu_core+0x7b5/0xf00 kernel/rcu/tree.c:2541
rcu_core_si+0x9/0x10 kernel/rcu/tree.c:2574
handle_softirqs+0x1d7/0x600 kernel/softirq.c:642
__do_softirq kernel/softirq.c:680 [inline]
invoke_softirq kernel/softirq.c:497 [inline]
__irq_exit_rcu+0x52/0xf0 kernel/softirq.c:729
irq_exit_rcu+0x9/0x10 kernel/softirq.c:741
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1118 [inline]
sysvec_apic_timer_interrupt+0xa9/0xc0 arch/x86/kernel/apic/apic.c:1118
asm_sysvec_apic_timer_interrupt+0x1b/0x20 arch/x86/include/asm/idtentry.h:691
RIP: 0010:free_swap_cache+0x13c/0x160 mm/swap_state.c:291
Code: 00 00 00 e8 76 0f bd ff 45 84 f6 75 07 e8 8c 0c bd ff eb 15 e8 85 0c bd ff 48 89 df e8 4d 71 00 00 48 89 df e8 85 3f e8 ff 5b <41> 5c 41 5e 41 5f 5d c3 e8 67 0c bd ff 49 ff ce 4c 89 f3 e9 02 ff
RSP: 0018:ffffc90006c9f6a0 EFLAGS: 00000293
RAX: ffffffff81b4596e RBX: 00000000000001fe RCX: ffff8881100e3cc0
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc90006c9f6b8 R08: ffffea000569f447 R09: 1ffffd4000ad3e88
R10: dffffc0000000000 R11: fffff94000ad3e89 R12: 0000000000080000
R13: dffffc0000000000 R14: 0000000000000000 R15: dffffc0000000000
free_pages_and_swap_cache+0x60/0xa0 mm/swap_state.c:315
tlb_batch_pages_flush mm/mmu_gather.c:59 [inline]
tlb_flush_mmu_free mm/mmu_gather.c:254 [inline]
tlb_flush_mmu mm/mmu_gather.c:261 [inline]
tlb_finish_mmu+0x1b2/0x380 mm/mmu_gather.c:361
exit_mmap+0x41d/0xc10 mm/mmap.c:3384
__mmput+0x92/0x340 kernel/fork.c:1319
mmput+0x4b/0x150 kernel/fork.c:1343
exit_mm kernel/exit.c:569 [inline]
do_exit+0xa51/0x2850 kernel/exit.c:874
do_group_exit+0x21b/0x2e0 kernel/exit.c:1030
get_signal+0x167c/0x1700 kernel/signal.c:2895
arch_do_signal_or_restart+0xd1/0x11c0 arch/x86/kernel/signal.c:871
exit_to_user_mode_loop+0x7a/0xb0 kernel/entry/common.c:174
exit_to_user_mode_prepare+0x87/0xd0 kernel/entry/common.c:210
__syscall_exit_to_user_mode_work kernel/entry/common.c:292 [inline]
syscall_exit_to_user_mode+0x1a/0x30 kernel/entry/common.c:303
do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:82
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f316cd9de99
Code: Unable to access opcode bytes at 0x7f316cd9de6f.
RSP: 002b:00007f316dd3f0e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: 0000000000000001 RBX: 00007f316d025fa8 RCX: 00007f316cd9de99
RDX: 00000000000f4240 RSI: 0000000000000081 RDI: 00007f316d025fac
RBP: 00007f316d025fa0 R08: 00000e5d028f0b78 R09: 0000000000000000
R10: ffffffffffffffff R11: 0000000000000246 R12: 0000000000000000
R13: 00007f316d026038 R14: 00007ffcabbe3770 R15: 00007ffcabbe3858
Allocated by task 6071:
kasan_save_stack mm/kasan/common.c:46 [inline]
kasan_set_track+0x4b/0x70 mm/kasan/common.c:53
kasan_save_alloc_info+0x1f/0x30 mm/kasan/generic.c:505
____kasan_kmalloc mm/kasan/common.c:380 [inline]
__kasan_kmalloc+0x95/0xb0 mm/kasan/common.c:389
kasan_kmalloc include/linux/kasan.h:212 [inline]
__do_kmalloc_node mm/slab_common.c:938 [inline]
__kmalloc+0xb4/0x1e0 mm/slab_common.c:951
kmalloc include/linux/slab.h:568 [inline]
kzalloc include/linux/slab.h:699 [inline]
l2tp_session_create+0x38/0xbd0 net/l2tp/l2tp_core.c:1609
pppol2tp_connect+0xbf5/0x1640 net/l2tp/l2tp_ppp.c:771
__sys_connect_file net/socket.c:2000 [inline]
__sys_connect+0x3da/0x460 net/socket.c:2017
__do_sys_connect net/socket.c:2027 [inline]
__se_sys_connect net/socket.c:2024 [inline]
__x64_sys_connect+0x7a/0x90 net/socket.c:2024
x64_sys_call+0x88d/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:43
do_syscall_x64 arch/x86/entry/common.c:46 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
entry_SYSCALL_64_after_hwframe+0x68/0xd2
Freed by task 407:
kasan_save_stack mm/kasan/common.c:46 [inline]
kasan_set_track+0x4b/0x70 mm/kasan/common.c:53
kasan_save_free_info+0x2b/0x40 mm/kasan/generic.c:516
____kasan_slab_free+0x132/0x180 mm/kasan/common.c:242
__kasan_slab_free+0x11/0x20 mm/kasan/common.c:250
kasan_slab_free include/linux/kasan.h:178 [inline]
slab_free_hook mm/slub.c:1750 [inline]
slab_free_freelist_hook+0xc2/0x190 mm/slub.c:1776
slab_free mm/slub.c:3712 [inline]
__kmem_cache_free+0xb7/0x1b0 mm/slub.c:3728
kfree+0x6f/0xf0 mm/slab_common.c:990
l2tp_session_free net/l2tp/l2tp_core.c:168 [inline]
l2tp_session_put+0xaf/0x1a0 net/l2tp/l2tp_core.c:193
l2tp_session_delete+0x3df/0x4d0 net/l2tp/l2tp_core.c:1582
l2tp_tunnel_closeall net/l2tp/l2tp_core.c:1228 [inline]
l2tp_tunnel_del_work+0x199/0x410 net/l2tp/l2tp_core.c:1266
process_one_work+0x717/0xc30 kernel/workqueue.c:2302
worker_thread+0xa4d/0x11d0 kernel/workqueue.c:2449
kthread+0x281/0x320 kernel/kthread.c:386
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
Last potentially related work creation:
kasan_save_stack+0x3a/0x60 mm/kasan/common.c:46
__kasan_record_aux_stack+0xb6/0xc0 mm/kasan/generic.c:486
kasan_record_aux_stack_noalloc+0xb/0x10 mm/kasan/generic.c:496
__call_rcu_common kernel/rcu/tree.c:2807 [inline]
call_rcu+0xcf/0xf50 kernel/rcu/tree.c:2926
pppol2tp_release+0x1e3/0x2b0 net/l2tp/l2tp_ppp.c:446
__sock_release net/socket.c:652 [inline]
sock_close+0xc9/0x220 net/socket.c:1389
__fput+0x1fd/0x8f0 fs/file_table.c:320
____fput+0x15/0x20 fs/file_table.c:348
task_work_run+0x1e1/0x250 kernel/task_work.c:203
resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
exit_to_user_mode_loop+0x9b/0xb0 kernel/entry/common.c:177
exit_to_user_mode_prepare+0x87/0xd0 kernel/entry/common.c:210
__syscall_exit_to_user_mode_work kernel/entry/common.c:292 [inline]
syscall_exit_to_user_mode+0x1a/0x30 kernel/entry/common.c:303
do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:82
entry_SYSCALL_64_after_hwframe+0x68/0xd2
Second to last potentially related work creation:
kasan_save_stack+0x3a/0x60 mm/kasan/common.c:46
__kasan_record_aux_stack+0xb6/0xc0 mm/kasan/generic.c:486
kasan_record_aux_stack_noalloc+0xb/0x10 mm/kasan/generic.c:496
__call_rcu_common kernel/rcu/tree.c:2807 [inline]
call_rcu+0xcf/0xf50 kernel/rcu/tree.c:2926
fib6_info_release include/net/ip6_fib.h:350 [inline]
__ip6_del_rt+0xf5/0x150 net/ipv6/route.c:3919
ip6_del_rt+0xbe/0x110 net/ipv6/route.c:3930
__ipv6_ifa_notify+0x877/0xe80 net/ipv6/addrconf.c:6267
addrconf_ifdown+0xdfd/0x1950 net/ipv6/addrconf.c:3948
addrconf_notify+0x39f/0xe30 net/ipv6/addrconf.c:-1
notifier_call_chain kernel/notifier.c:87 [inline]
raw_notifier_call_chain+0xa1/0x110 kernel/notifier.c:455
call_netdevice_notifiers_info net/core/dev.c:2022 [inline]
call_netdevice_notifiers_extack net/core/dev.c:2060 [inline]
call_netdevice_notifiers net/core/dev.c:2074 [inline]
dev_close_many+0x325/0x4d0 net/core/dev.c:1622
unregister_netdevice_many+0x43f/0x1910 net/core/dev.c:10979
default_device_exit_batch+0x951/0x9f0 net/core/dev.c:11518
ops_exit_list net/core/net_namespace.c:177 [inline]
cleanup_net+0x630/0xb10 net/core/net_namespace.c:604
process_one_work+0x717/0xc30 kernel/workqueue.c:2302
worker_thread+0xa4d/0x11d0 kernel/workqueue.c:2449
kthread+0x281/0x320 kernel/kthread.c:386
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
The buggy address belongs to the object at ffff8881321fa000
which belongs to the cache kmalloc-512 of size 512
The buggy address is located 400 bytes inside of
512-byte region [ffff8881321fa000, ffff8881321fa200)
The buggy address belongs to the physical page:
page:ffffea0004c87e00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1321f8
head:ffffea0004c87e00 order:2 compound_mapcount:0 compound_pincount:0
flags: 0x4000000000010200(slab|head|zone=1)
raw: 4000000000010200 ffffea00044a7100 dead000000000002 ffff888100042f00
raw: 0000000000000000 0000000080100010 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 0x52a20(GFP_ATOMIC|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP), pid 289, tgid 289 (syz-executor), ts 24762172861, free_ts 0
set_page_owner include/linux/page_owner.h:33 [inline]
post_alloc_hook+0x1f5/0x210 mm/page_alloc.c:2672
prep_new_page+0x1c/0x110 mm/page_alloc.c:2679
get_page_from_freelist+0x2ca9/0x2d20 mm/page_alloc.c:4586
__alloc_pages+0x1fa/0x610 mm/page_alloc.c:5930
alloc_slab_page+0x6e/0xf0 include/linux/gfp.h:-1
allocate_slab mm/slub.c:1967 [inline]
new_slab+0x98/0x3e0 mm/slub.c:2020
___slab_alloc+0x70f/0xb70 mm/slub.c:3177
__slab_alloc+0x5e/0xa0 mm/slub.c:3263
slab_alloc_node mm/slub.c:3348 [inline]
__kmem_cache_alloc_node+0x204/0x2d0 mm/slub.c:3423
__do_kmalloc_node mm/slab_common.c:937 [inline]
__kmalloc+0xa4/0x1e0 mm/slab_common.c:951
kmalloc include/linux/slab.h:568 [inline]
kzalloc include/linux/slab.h:699 [inline]
fib6_info_alloc+0x34/0xe0 net/ipv6/ip6_fib.c:156
ip6_route_info_create+0x51b/0x14d0 net/ipv6/route.c:3796
addrconf_f6i_alloc+0x19c/0x3f0 net/ipv6/route.c:4600
fixup_permanent_addr net/ipv6/addrconf.c:3554 [inline]
addrconf_permanent_addr+0x237/0x940 net/ipv6/addrconf.c:3593
addrconf_notify+0x7ca/0xe30 net/ipv6/addrconf.c:3665
notifier_call_chain kernel/notifier.c:87 [inline]
raw_notifier_call_chain+0xa1/0x110 kernel/notifier.c:455
page_owner free stack trace missing
Memory state around the buggy address:
ffff8881321fa080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff8881321fa100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff8881321fa180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff8881321fa200: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff8881321fa280: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================
----------------
Code disassembly (best guess):
0: 00 00 add %al,(%rax)
2: 00 e8 add %ch,%al
4: 76 0f jbe 0x15
6: bd ff 45 84 f6 mov $0xf68445ff,%ebp
b: 75 07 jne 0x14
d: e8 8c 0c bd ff call 0xffbd0c9e
12: eb 15 jmp 0x29
14: e8 85 0c bd ff call 0xffbd0c9e
19: 48 89 df mov %rbx,%rdi
1c: e8 4d 71 00 00 call 0x716e
21: 48 89 df mov %rbx,%rdi
24: e8 85 3f e8 ff call 0xffe83fae
29: 5b pop %rbx
* 2a: 41 5c pop %r12 <-- trapping instruction
2c: 41 5e pop %r14
2e: 41 5f pop %r15
30: 5d pop %rbp
31: c3 ret
32: e8 67 0c bd ff call 0xffbd0c9e
37: 49 ff ce dec %r14
3a: 4c 89 f3 mov %r14,%rbx
3d: e9 .byte 0xe9
3e: 02 ff add %bh,%bh