==================================================================
BUG: KASAN: use-after-free in rcu_cblist_dequeue+0x6c/0xb0 kernel/rcu/rcu_segcblist.c:75
Read of size 8 at addr ffff888102dbbd90 by task syz.1.1072/4638
CPU: 1 PID: 4638 Comm: syz.1.1072 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:kasan_check_range+0x1c6/0x2a0 mm/kasan/generic.c:-1
Code: 89 dc 49 8d 5c 24 07 4d 85 e4 49 0f 49 dc 48 83 e3 f8 49 29 dc 74 0e 41 80 3b 00 75 6b 49 ff c3 49 ff cc 75 f2 5b 41 5c 41 5d <41> 5e 41 5f 5d c3 45 84 ff 0f 85 91 00 00 00 41 f7 c7 00 ff 00 00
RSP: 0018:ffffc90000e77c98 EFLAGS: 00000256
RAX: ffffffff8155d301 RBX: 0000000000000050 RCX: ffffffff8155d402
RDX: 0000000000000001 RSI: 0000000000000050 RDI: ffffc90000e77d20
RBP: ffffc90000e77ca8 R08: ffffc90000e77d6f R09: 1ffff920001cefad
R10: dffffc0000000000 R11: fffff520001cefae R12: 00000000000f4240
R13: dffffc0000000000 R14: 1ffff920001cefa4 R15: ffffc90000e77d20
memset+0x23/0x40 mm/kasan/shadow.c:44
hrtimer_nanosleep+0xb2/0x400 kernel/time/hrtimer.c:1989
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: 0033:0x7f4e0ba02a0e
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:00007fffc06d5518 EFLAGS: 00000246 ORIG_RAX: 00000000000000e6
RAX: ffffffffffffffda RBX: 000055556608e500 RCX: 00007f4e0ba02a0e
RDX: 00007fffc06d5570 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007f4e0bccbda0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000002eead
R13: 00007f4e0bcca09c R14: 000000000002ebdf R15: 00007f4e0bcca090
Allocated by task 4627:
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
The buggy address belongs to the object at ffff888102dbbc00
which belongs to the cache kmalloc-512 of size 512
The buggy address is located 400 bytes inside of
512-byte region [ffff888102dbbc00, ffff888102dbbe00)
The buggy address belongs to the page:
page:ffffea00040b6e00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x102db8
head:ffffea00040b6e00 order:2 compound_mapcount:0 compound_pincount:0
flags: 0x4000000000010200(slab|head)
raw: 4000000000010200 ffffea00042f2200 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 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 280, ts 22574904034, free_ts 22570674799
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]
inet_netconf_notify_devconf+0x169/0x220 net/ipv4/devinet.c:2120
__devinet_sysctl_register+0x31c/0x390 net/ipv4/devinet.c:2604
devinet_sysctl_register+0x169/0x1e0 net/ipv4/devinet.c:2638
inetdev_init+0x26c/0x490 net/ipv4/devinet.c:277
inetdev_event+0x1f4/0x1010 net/ipv4/devinet.c:1544
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 last free stack trace:
reset_page_owner include/linux/page_owner.h:28 [inline]
free_pages_prepare mm/page_alloc.c:1349 [inline]
__free_pages_ok+0x80b/0x830 mm/page_alloc.c:1629
free_the_page mm/page_alloc.c:5445 [inline]
__free_pages+0xd8/0x390 mm/page_alloc.c:5454
__free_slab+0xcf/0x190 mm/slub.c:1899
free_slab mm/slub.c:1914 [inline]
discard_slab mm/slub.c:1920 [inline]
unfreeze_partials+0x150/0x180 mm/slub.c:2415
put_cpu_partial+0xc1/0x180 mm/slub.c:2451
__slab_free+0x2c9/0x3a0 mm/slub.c:3100
do_slab_free mm/slub.c:3196 [inline]
___cache_free+0x10e/0x130 mm/slub.c:3215
qlink_free+0x50/0x90 mm/kasan/quarantine.c:157
qlist_free_all+0x5f/0xb0 mm/kasan/quarantine.c:176
kasan_quarantine_reduce+0x14a/0x160 mm/kasan/quarantine.c:283
__kasan_slab_alloc+0x2f/0xe0 mm/kasan/common.c:440
kasan_slab_alloc include/linux/kasan.h:244 [inline]
slab_post_alloc_hook+0x5d/0x2f0 mm/slab.h:580
slab_alloc_node mm/slub.c:2952 [inline]
slab_alloc mm/slub.c:2960 [inline]
__kmalloc_track_caller+0x176/0x310 mm/slub.c:4541
kvasprintf+0xe3/0x1a0 lib/kasprintf.c:25
kvasprintf_const+0xf2/0x240 lib/kasprintf.c:49
kobject_set_name_vargs+0x61/0x110 lib/kobject.c:297
Memory state around the buggy address:
ffff888102dbbc80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888102dbbd00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888102dbbd80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff888102dbbe00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff888102dbbe80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================
----------------
Code disassembly (best guess):
0: 89 dc mov %ebx,%esp
2: 49 8d 5c 24 07 lea 0x7(%r12),%rbx
7: 4d 85 e4 test %r12,%r12
a: 49 0f 49 dc cmovns %r12,%rbx
e: 48 83 e3 f8 and $0xfffffffffffffff8,%rbx
12: 49 29 dc sub %rbx,%r12
15: 74 0e je 0x25
17: 41 80 3b 00 cmpb $0x0,(%r11)
1b: 75 6b jne 0x88
1d: 49 ff c3 inc %r11
20: 49 ff cc dec %r12
23: 75 f2 jne 0x17
25: 5b pop %rbx
26: 41 5c pop %r12
28: 41 5d pop %r13
* 2a: 41 5e pop %r14 <-- trapping instruction
2c: 41 5f pop %r15
2e: 5d pop %rbp
2f: c3 ret
30: 45 84 ff test %r15b,%r15b
33: 0f 85 91 00 00 00 jne 0xca
39: 41 f7 c7 00 ff 00 00 test $0xff00,%r15d