==================================================================
BUG: KASAN: use-after-free in rcu_cblist_dequeue+0x6c/0xb0 kernel/rcu/rcu_segcblist.c:75
Read of size 8 at addr ffff88812cbb8190 by task kworker/0:5/1150
CPU: 0 PID: 1150 Comm: kworker/0:5 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Workqueue: usb_hub_wq hub_event
Call Trace:
__dump_stack+0x21/0x30 lib/dump_stack.c:88
dump_stack_lvl+0x110/0x170 lib/dump_stack.c:106
print_address_description+0x7f/0x2c0 mm/kasan/report.c:248
__kasan_report mm/kasan/report.c:427 [inline]
kasan_report+0x10f/0x150 mm/kasan/report.c:444
__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+0x47d/0xbf0 kernel/rcu/tree.c:2512
rcu_core+0x4a3/0xef0 kernel/rcu/tree.c:2763
rcu_core_si+0x9/0x10 kernel/rcu/tree.c:2776
handle_softirqs+0x250/0x560 kernel/softirq.c:583
__do_softirq kernel/softirq.c:621 [inline]
invoke_softirq kernel/softirq.c:443 [inline]
__irq_exit_rcu+0x52/0xf0 kernel/softirq.c:670
irq_exit_rcu+0x9/0x10 kernel/softirq.c:682
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline]
sysvec_apic_timer_interrupt+0xa9/0xc0 arch/x86/kernel/apic/apic.c:1108
asm_sysvec_apic_timer_interrupt+0x1b/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:console_unlock+0xb32/0xf10 kernel/printk/printk.c:2775
Code: 28 4c 89 f6 48 81 e6 00 02 00 00 31 ff e8 56 d4 17 00 49 81 e6 00 02 00 00 75 07 e8 08 d0 17 00 eb 06 e8 01 d0 17 00 fb 89 d8 <0a> 44 24 1f a8 01 74 0e e8 f1 cf 17 00 85 db 74 19 e9 1b 03 00 00
RSP: 0018:ffffc90000d77240 EFLAGS: 00000287
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000100000
RDX: ffffc90008ccb000 RSI: 00000000000027f8 RDI: 00000000000027f9
RBP: ffffc90000d774b0 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffff520001aee38 R12: 0000000000000053
R13: fffff520001aee54 R14: 0000000000000200 R15: dffffc0000000000
vprintk_emit+0x13f/0x320 kernel/printk/printk.c:2294
dev_vprintk_emit+0x2c5/0x360 drivers/base/core.c:4660
dev_printk_emit+0xeb/0x140 drivers/base/core.c:4671
__dev_printk+0x17f/0x1b0 drivers/base/core.c:4683
_dev_info+0x11b/0x170 drivers/base/core.c:4729
hub_port_init+0x731/0x2760 drivers/usb/core/hub.c:4984
hub_port_connect drivers/usb/core/hub.c:5489 [inline]
hub_port_connect_change drivers/usb/core/hub.c:5700 [inline]
port_event drivers/usb/core/hub.c:5866 [inline]
hub_event+0x2542/0x43f0 drivers/usb/core/hub.c:5948
process_one_work+0x6c8/0xbb0 kernel/workqueue.c:2328
worker_thread+0xaa0/0x1250 kernel/workqueue.c:2475
kthread+0x3f5/0x4f0 kernel/kthread.c:337
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
Allocated by task 4720:
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:433 [inline]
____kasan_kmalloc mm/kasan/common.c:512 [inline]
__kasan_kmalloc+0xd4/0x100 mm/kasan/common.c:521
kasan_kmalloc include/linux/kasan.h:227 [inline]
__kmalloc+0x13d/0x2c0 mm/slub.c:4436
kmalloc include/linux/slab.h:624 [inline]
kzalloc include/linux/slab.h:750 [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:1923 [inline]
__sys_connect+0x3cb/0x450 net/socket.c:1940
__do_sys_connect net/socket.c:1950 [inline]
__se_sys_connect net/socket.c:1947 [inline]
__x64_sys_connect+0x7a/0x90 net/socket.c:1947
x64_sys_call+0x7c/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:43
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x66/0xd0
Freed by task 331:
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:365
__kasan_slab_free+0x11/0x20 mm/kasan/common.c:373
kasan_slab_free include/linux/kasan.h:193 [inline]
slab_free_hook mm/slub.c:1728 [inline]
slab_free_freelist_hook+0xc2/0x190 mm/slub.c:1754
slab_free mm/slub.c:3526 [inline]
kfree+0xc4/0x270 mm/slub.c:4588
l2tp_session_free net/l2tp/l2tp_core.c:168 [inline]
l2tp_session_put+0xaf/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+0x6c8/0xbb0 kernel/workqueue.c:2328
worker_thread+0xaa0/0x1250 kernel/workqueue.c:2475
kthread+0x3f5/0x4f0 kernel/kthread.c:337
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
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_common kernel/rcu/tree.c:3011 [inline]
call_rcu+0x10b/0xf60 kernel/rcu/tree.c:3129
pppol2tp_release+0x1e3/0x2b0 net/l2tp/l2tp_ppp.c:447
__sock_release net/socket.c:649 [inline]
sock_close+0xb8/0x200 net/socket.c:1336
__fput+0x22b/0x900 fs/file_table.c:311
____fput+0x15/0x20 fs/file_table.c:339
task_work_run+0x127/0x190 kernel/task_work.c:188
tracehook_notify_resume include/linux/tracehook.h:189 [inline]
exit_to_user_mode_loop+0xd0/0xe0 kernel/entry/common.c:184
exit_to_user_mode_prepare+0x87/0xd0 kernel/entry/common.c:217
__syscall_exit_to_user_mode_work kernel/entry/common.c:299 [inline]
syscall_exit_to_user_mode+0x1a/0x30 kernel/entry/common.c:310
do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:86
entry_SYSCALL_64_after_hwframe+0x66/0xd0
The buggy address belongs to the object at ffff88812cbb8000
which belongs to the cache kmalloc-512 of size 512
The buggy address is located 400 bytes inside of
512-byte region [ffff88812cbb8000, ffff88812cbb8200)
The buggy address belongs to the page:
page:ffffea0004b2ee00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x12cbb8
head:ffffea0004b2ee00 order:2 compound_mapcount:0 compound_pincount:0
flags: 0x4000000000010200(slab|head|zone=1)
raw: 4000000000010200 ffffea0004421400 0000000200000002 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 0x152a20(GFP_ATOMIC|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_HARDWALL), pid 440, ts 36443387886, free_ts 36443078545
set_page_owner include/linux/page_owner.h:33 [inline]
post_alloc_hook+0x192/0x1b0 mm/page_alloc.c:2607
prep_new_page+0x1c/0x110 mm/page_alloc.c:2613
get_page_from_freelist+0x2c3a/0x2cd0 mm/page_alloc.c:4487
__alloc_pages+0x1a2/0x460 mm/page_alloc.c:5824
alloc_slab_page mm/slub.c:-1 [inline]
allocate_slab mm/slub.c:1937 [inline]
new_slab+0xa0/0x4d0 mm/slub.c:2000
___slab_alloc+0x3ac/0x840 mm/slub.c:3033
__slab_alloc+0x49/0x90 mm/slub.c:3120
slab_alloc_node mm/slub.c:3211 [inline]
slab_alloc mm/slub.c:3255 [inline]
__kmalloc+0x16a/0x2c0 mm/slub.c:4432
kmalloc include/linux/slab.h:624 [inline]
kzalloc include/linux/slab.h:750 [inline]
neigh_alloc net/core/neighbour.c:438 [inline]
___neigh_create+0x6fb/0x1c50 net/core/neighbour.c:591
__neigh_create+0x31/0x40 net/core/neighbour.c:679
ip6_finish_output2+0xae3/0x1790 net/ipv6/ip6_output.c:129
__ip6_finish_output+0x623/0x7e0 net/ipv6/ip6_output.c:203
ip6_finish_output+0x31/0x220 net/ipv6/ip6_output.c:213
NF_HOOK_COND include/linux/netfilter.h:294 [inline]
ip6_output+0x1fa/0x410 net/ipv6/ip6_output.c:236
dst_output include/net/dst.h:453 [inline]
NF_HOOK include/linux/netfilter.h:305 [inline]
ndisc_send_skb+0x7f8/0xd00 net/ipv6/ndisc.c:513
ndisc_send_rs+0x711/0x960 net/ipv6/ndisc.c:707
page last free stack trace:
reset_page_owner include/linux/page_owner.h:26 [inline]
free_pages_prepare mm/page_alloc.c:1474 [inline]
free_pcp_prepare mm/page_alloc.c:1546 [inline]
free_unref_page_prepare+0x5fa/0x600 mm/page_alloc.c:3536
free_unref_page+0xae/0x540 mm/page_alloc.c:3618
free_the_page mm/page_alloc.c:805 [inline]
__free_pages+0x6c/0x100 mm/page_alloc.c:5900
free_pages+0x82/0x90 mm/page_alloc.c:5911
__stack_depot_save+0x453/0x480 lib/stackdepot.c:358
kasan_save_stack mm/kasan/common.c:39 [inline]
kasan_set_track+0x5b/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:365
__kasan_slab_free+0x11/0x20 mm/kasan/common.c:373
kasan_slab_free include/linux/kasan.h:193 [inline]
slab_free_hook mm/slub.c:1728 [inline]
slab_free_freelist_hook+0xc2/0x190 mm/slub.c:1754
slab_free mm/slub.c:3526 [inline]
kmem_cache_free+0x100/0x320 mm/slub.c:3544
kfree_skbmem+0x10c/0x180 net/core/skbuff.c:-1
__kfree_skb net/core/skbuff.c:758 [inline]
consume_skb+0xb3/0x1f0 net/core/skbuff.c:934
tpacket_rcv+0x1350/0x3060 net/packet/af_packet.c:2534
dev_queue_xmit_nit+0x939/0x9c0 net/core/dev.c:2394
xmit_one net/core/dev.c:3665 [inline]
dev_hard_start_xmit+0x163/0x680 net/core/dev.c:3686
Memory state around the buggy address:
ffff88812cbb8080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88812cbb8100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88812cbb8180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff88812cbb8200: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff88812cbb8280: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================
----------------
Code disassembly (best guess):
0: 28 4c 89 f6 sub %cl,-0xa(%rcx,%rcx,4)
4: 48 81 e6 00 02 00 00 and $0x200,%rsi
b: 31 ff xor %edi,%edi
d: e8 56 d4 17 00 call 0x17d468
12: 49 81 e6 00 02 00 00 and $0x200,%r14
19: 75 07 jne 0x22
1b: e8 08 d0 17 00 call 0x17d028
20: eb 06 jmp 0x28
22: e8 01 d0 17 00 call 0x17d028
27: fb sti
28: 89 d8 mov %ebx,%eax
* 2a: 0a 44 24 1f or 0x1f(%rsp),%al <-- trapping instruction
2e: a8 01 test $0x1,%al
30: 74 0e je 0x40
32: e8 f1 cf 17 00 call 0x17d028
37: 85 db test %ebx,%ebx
39: 74 19 je 0x54
3b: e9 1b 03 00 00 jmp 0x35b