==================================================================
BUG: KASAN: use-after-free in rcu_cblist_dequeue+0x6c/0xb0 kernel/rcu/rcu_segcblist.c:75
Read of size 8 at addr ffff888113b71d90 by task syz.5.3966/13707
CPU: 0 PID: 13707 Comm: syz.5.3966 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/15/2026
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_cblist_dequeue+0x6c/0xb0 kernel/rcu/rcu_segcblist.c:75
rcu_do_batch+0x4bc/0xc30 kernel/rcu/tree.c:2285
rcu_core+0x486/0xf00 kernel/rcu/tree.c:2557
rcu_core_si+0x9/0x10 kernel/rcu/tree.c:2574
handle_softirqs+0x1dd/0x5f0 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:__sanitizer_cov_trace_pc+0x49/0x60 kernel/kcov.c:222
Code: 81 fa 00 01 00 00 75 35 83 b9 6c 0b 00 00 00 74 2c 8b 91 48 0b 00 00 83 fa 02 75 21 48 8b 91 50 0b 00 00 48 8b 32 48 8d 7e 01 <8b> 89 4c 0b 00 00 48 39 cf 73 08 48 89 3a 48 89 44 f2 08 5d c3 66
RSP: 0018:ffffc90000f97720 EFLAGS: 00000246
RAX: ffffffff84f5172f RBX: 1ffff110287a7d80 RCX: ffff888128736540
RDX: ffffc9000778f000 RSI: 0000000000054626 RDI: 0000000000054627
RBP: ffffc90000f97720 R08: ffffc90000f97857 R09: ffffc90000f97840
R10: dffffc0000000000 R11: fffff520001f2f0b R12: 0000000000000000
R13: ffff888143d3ec00 R14: 000000000000007e R15: ffff888143d3ec02
get_offset lib/xarray.c:144 [inline]
xas_descend lib/xarray.c:203 [inline]
xas_load+0x11f/0x3c0 lib/xarray.c:242
mapping_get_entry mm/filemap.c:1918 [inline]
__filemap_get_folio+0x151/0xa70 mm/filemap.c:1980
shmem_get_folio_gfp+0x2fb/0x20f0 mm/shmem.c:1891
shmem_get_folio mm/shmem.c:2082 [inline]
shmem_write_begin+0xea/0x2c0 mm/shmem.c:2567
generic_perform_write+0x32d/0x740 mm/filemap.c:3927
__generic_file_write_iter+0x17a/0x230 mm/filemap.c:4026
generic_file_write_iter+0xae/0x310 mm/filemap.c:4055
call_write_iter include/linux/fs.h:2282 [inline]
new_sync_write fs/read_write.c:491 [inline]
vfs_write+0x5ef/0xd00 fs/read_write.c:584
ksys_write+0x14a/0x260 fs/read_write.c:637
__do_sys_write fs/read_write.c:649 [inline]
__se_sys_write fs/read_write.c:646 [inline]
__x64_sys_write+0x7b/0x90 fs/read_write.c:646
x64_sys_call+0x27b/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:2
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
RIP: 0033:0x7fc077d6034e
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:00007fc078c21da8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007fc078c226c0 RCX: 00007fc077d6034e
RDX: 00000000013bd7ef RSI: 00007fc06e3f8000 RDI: 0000000000000003
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000003
R13: 00007fc078c21ee0 R14: 00007fc078c21ea0 R15: 00007fc06e3f8000
Allocated by task 13714:
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:1614
pppol2tp_connect+0xbf5/0x1640 net/l2tp/l2tp_ppp.c:771
__sys_connect_file net/socket.c:2001 [inline]
__sys_connect+0x3da/0x460 net/socket.c:2018
__do_sys_connect net/socket.c:2028 [inline]
__se_sys_connect net/socket.c:2025 [inline]
__x64_sys_connect+0x7a/0x90 net/socket.c:2025
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 10:
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:1587
l2tp_tunnel_closeall net/l2tp/l2tp_core.c:1233 [inline]
l2tp_tunnel_del_work+0x199/0x410 net/l2tp/l2tp_core.c:1271
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:1390
__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
exit_task_work include/linux/task_work.h:39 [inline]
do_exit+0xb0d/0x29f0 kernel/exit.c:896
do_group_exit+0x21b/0x2e0 kernel/exit.c:1040
get_signal+0x167c/0x1700 kernel/signal.c:2904
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
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]
fib6_del_route net/ipv6/ip6_fib.c:2004 [inline]
fib6_del+0xbda/0xef0 net/ipv6/ip6_fib.c:2037
fib6_clean_node+0x2af/0x550 net/ipv6/ip6_fib.c:2199
fib6_walk_continue+0x55d/0x760 net/ipv6/ip6_fib.c:2121
fib6_walk+0x153/0x290 net/ipv6/ip6_fib.c:2169
fib6_clean_tree net/ipv6/ip6_fib.c:2249 [inline]
__fib6_clean_all net/ipv6/ip6_fib.c:2265 [inline]
fib6_clean_all+0x1a1/0x270 net/ipv6/ip6_fib.c:2276
rt6_sync_down_dev net/ipv6/route.c:4926 [inline]
rt6_disable_ip+0x123/0x8e0 net/ipv6/route.c:4931
addrconf_ifdown+0x15d/0x1950 net/ipv6/addrconf.c:3824
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:10980
default_device_exit_batch+0x951/0x9f0 net/core/dev.c:11519
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 ffff888113b71c00
which belongs to the cache kmalloc-512 of size 512
The buggy address is located 400 bytes inside of
512-byte region [ffff888113b71c00, ffff888113b71e00)
The buggy address belongs to the physical page:
page:ffffea00044edc00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x113b70
head:ffffea00044edc00 order:2 compound_mapcount:0 compound_pincount:0
flags: 0x4000000000010200(slab|head|zone=1)
raw: 4000000000010200 0000000000000000 dead000000000001 ffff888100042f00
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 0x1d20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_HARDWALL), pid 9812, tgid 9812 (syz-executor), ts 464557520881, free_ts 463604004382
set_page_owner include/linux/page_owner.h:33 [inline]
post_alloc_hook+0x1f5/0x210 mm/page_alloc.c:2673
prep_new_page+0x1c/0x110 mm/page_alloc.c:2680
get_page_from_freelist+0x2ca9/0x2d20 mm/page_alloc.c:4587
__alloc_pages+0x1fa/0x610 mm/page_alloc.c:5931
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_node_track_caller+0xa1/0x1e0 mm/slab_common.c:958
kmalloc_reserve net/core/skbuff.c:449 [inline]
__alloc_skb+0x226/0x4a0 net/core/skbuff.c:518
alloc_skb include/linux/skbuff.h:1322 [inline]
nlmsg_new include/net/netlink.h:987 [inline]
netlink_ack+0x373/0x1160 net/netlink/af_netlink.c:2463
netlink_rcv_skb+0x27e/0x450 net/netlink/af_netlink.c:2532
rtnetlink_rcv+0x1c/0x20 net/core/rtnetlink.c:6180
netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline]
netlink_unicast+0x8c1/0xa60 net/netlink/af_netlink.c:1345
netlink_sendmsg+0x8b9/0xbd0 net/netlink/af_netlink.c:1878
page last free stack trace:
reset_page_owner include/linux/page_owner.h:26 [inline]
free_pages_prepare mm/page_alloc.c:1581 [inline]
free_pcp_prepare mm/page_alloc.c:1655 [inline]
free_unref_page_prepare+0x81b/0x820 mm/page_alloc.c:3622
free_unref_page+0x93/0x530 mm/page_alloc.c:3720
free_the_page mm/page_alloc.c:863 [inline]
__free_pages+0x67/0x100 mm/page_alloc.c:6021
__free_slab+0xc7/0x1a0 mm/slub.c:2044
free_slab mm/slub.c:2059 [inline]
discard_slab+0x29/0x40 mm/slub.c:2065
__slab_free+0x201/0x280 mm/slub.c:3625
do_slab_free mm/slub.c:3666 [inline]
___cache_free+0xbf/0xd0 mm/slub.c:3722
qlink_free mm/kasan/quarantine.c:168 [inline]
qlist_free_all+0xc6/0x140 mm/kasan/quarantine.c:187
kasan_quarantine_reduce+0x14a/0x170 mm/kasan/quarantine.c:294
__kasan_slab_alloc+0x24/0x80 mm/kasan/common.c:311
kasan_slab_alloc include/linux/kasan.h:202 [inline]
slab_post_alloc_hook+0x4f/0x2d0 mm/slab.h:768
slab_alloc_node mm/slub.c:3382 [inline]
kmem_cache_alloc_node+0x179/0x330 mm/slub.c:3429
__alloc_skb+0xe8/0x4a0 net/core/skbuff.c:508
alloc_skb include/linux/skbuff.h:1322 [inline]
netlink_dump+0x1e8/0xdc0 net/netlink/af_netlink.c:2217
__netlink_dump_start+0x645/0x860 net/netlink/af_netlink.c:2353
netlink_dump_start include/linux/netlink.h:269 [inline]
rtnetlink_rcv_msg+0xcb2/0xde0 net/core/rtnetlink.c:6118
Memory state around the buggy address:
ffff888113b71c80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888113b71d00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888113b71d80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff888113b71e00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff888113b71e80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================
----------------
Code disassembly (best guess):
0: 81 fa 00 01 00 00 cmp $0x100,%edx
6: 75 35 jne 0x3d
8: 83 b9 6c 0b 00 00 00 cmpl $0x0,0xb6c(%rcx)
f: 74 2c je 0x3d
11: 8b 91 48 0b 00 00 mov 0xb48(%rcx),%edx
17: 83 fa 02 cmp $0x2,%edx
1a: 75 21 jne 0x3d
1c: 48 8b 91 50 0b 00 00 mov 0xb50(%rcx),%rdx
23: 48 8b 32 mov (%rdx),%rsi
26: 48 8d 7e 01 lea 0x1(%rsi),%rdi
* 2a: 8b 89 4c 0b 00 00 mov 0xb4c(%rcx),%ecx <-- trapping instruction
30: 48 39 cf cmp %rcx,%rdi
33: 73 08 jae 0x3d
35: 48 89 3a mov %rdi,(%rdx)
38: 48 89 44 f2 08 mov %rax,0x8(%rdx,%rsi,8)
3d: 5d pop %rbp
3e: c3 ret
3f: 66 data16