==================================================================
BUG: KASAN: use-after-free in rcu_cblist_dequeue+0x6c/0xb0 kernel/rcu/rcu_segcblist.c:75
Read of size 8 at addr ffff88811116b190 by task syz.1.28/430
CPU: 1 PID: 430 Comm: syz.1.28 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
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:should_resched arch/x86/include/asm/preempt.h:103 [inline]
RIP: 0010:__local_bh_enable_ip+0x58/0x80 kernel/softirq.c:404
Code: a9 00 ff ff 00 75 19 48 c7 c7 40 2c 08 85 e8 4f f8 6e 03 65 66 8b 05 47 43 c4 7e 66 85 c0 75 22 bf 01 00 00 00 e8 08 98 08 00 <65> 8b 05 b9 40 c3 7e 85 c0 74 02 5d c3 e8 5a 4c c1 ff 5d c3 0f 0b
RSP: 0018:ffffc900010aefd8 EFLAGS: 00000297
RAX: 0000000080000001 RBX: ffffc9000856b02c RCX: 0000000000000000
RDX: ffffc9000137b000 RSI: ffffffff85082c40 RDI: 00000000ffffffff
RBP: ffffc900010aefd8 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffff52000215df0 R12: dffffc0000000000
R13: 0000000000000000 R14: 0000000000000001 R15: ffffc9000891d1d8
__raw_spin_unlock_bh include/linux/spinlock_api_smp.h:176 [inline]
_raw_spin_unlock_bh+0x51/0x60 kernel/locking/spinlock.c:210
spin_unlock_bh include/linux/spinlock.h:409 [inline]
htable_selective_cleanup+0x297/0x320 net/netfilter/xt_hashlimit.c:374
htable_put+0x240/0x2a0 net/netfilter/xt_hashlimit.c:430
hashlimit_mt_destroy+0x5c/0x70 net/netfilter/xt_hashlimit.c:977
cleanup_match net/ipv6/netfilter/ip6_tables.c:479 [inline]
cleanup_entry+0x156/0x350 net/ipv6/netfilter/ip6_tables.c:663
translate_table+0x1e09/0x2020 net/ipv6/netfilter/ip6_tables.c:746
do_replace net/ipv6/netfilter/ip6_tables.c:1154 [inline]
do_ip6t_set_ctl+0x960/0xd80 net/ipv6/netfilter/ip6_tables.c:1643
nf_setsockopt+0x272/0x2a0 net/netfilter/nf_sockopt.c:101
ipv6_setsockopt+0x258f/0x3750 net/ipv6/ipv6_sockglue.c:1011
rawv6_setsockopt+0x29e/0x660 net/ipv6/raw.c:1089
sock_common_setsockopt+0xa0/0xb0 net/core/sock.c:3469
__sys_setsockopt+0x2e9/0x470 net/socket.c:2203
__do_sys_setsockopt net/socket.c:2214 [inline]
__se_sys_setsockopt net/socket.c:2211 [inline]
__x64_sys_setsockopt+0xbf/0xd0 net/socket.c:2211
x64_sys_call+0x982/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:55
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
RIP: 0033:0x7f6365f70e99
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f63649ca028 EFLAGS: 00000246 ORIG_RAX: 0000000000000036
RAX: ffffffffffffffda RBX: 00007f63661f8fa0 RCX: 00007f6365f70e99
RDX: 0000000000000040 RSI: 0000000000000029 RDI: 0000000000000005
RBP: 00007f6366006eaf R08: 0000000000000528 R09: 0000000000000000
R10: 0000200000000440 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f63661f9038 R14: 00007f63661f8fa0 R15: 00007ffffcca30d8
Allocated by task 447:
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 350:
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:181
exit_to_user_mode_prepare+0x87/0xd0 kernel/entry/common.c:214
__syscall_exit_to_user_mode_work kernel/entry/common.c:296 [inline]
syscall_exit_to_user_mode+0x1a/0x30 kernel/entry/common.c:307
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 ffff88811116b000
which belongs to the cache kmalloc-512 of size 512
The buggy address is located 400 bytes inside of
512-byte region [ffff88811116b000, ffff88811116b200)
The buggy address belongs to the page:
page:ffffea0004445a00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x111168
head:ffffea0004445a00 order:2 compound_mapcount:0 compound_pincount:0
flags: 0x4000000000010200(slab|head|zone=1)
raw: 4000000000010200 ffffea00044d9800 0000000400000004 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 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 114, ts 4215137601, free_ts 0
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_track_caller+0x169/0x2c0 mm/slub.c:4954
kmalloc_reserve net/core/skbuff.c:357 [inline]
__alloc_skb+0x210/0x730 net/core/skbuff.c:428
alloc_skb include/linux/skbuff.h:1183 [inline]
alloc_skb_with_frags+0xa8/0x620 net/core/skbuff.c:6207
sock_alloc_send_pskb+0x87f/0x9a0 net/core/sock.c:2542
unix_dgram_sendmsg+0x6f3/0x19b0 net/unix/af_unix.c:1816
sock_sendmsg_nosec net/socket.c:704 [inline]
__sock_sendmsg net/socket.c:716 [inline]
sock_write_iter+0x2a6/0x3a0 net/socket.c:1080
call_write_iter include/linux/fs.h:2212 [inline]
new_sync_write fs/read_write.c:507 [inline]
vfs_write+0x831/0xfd0 fs/read_write.c:594
ksys_write+0x14a/0x260 fs/read_write.c:647
__do_sys_write fs/read_write.c:659 [inline]
__se_sys_write fs/read_write.c:656 [inline]
__x64_sys_write+0x7b/0x90 fs/read_write.c:656
page_owner free stack trace missing
Memory state around the buggy address:
ffff88811116b080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88811116b100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88811116b180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff88811116b200: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff88811116b280: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================
----------------
Code disassembly (best guess):
0: a9 00 ff ff 00 test $0xffff00,%eax
5: 75 19 jne 0x20
7: 48 c7 c7 40 2c 08 85 mov $0xffffffff85082c40,%rdi
e: e8 4f f8 6e 03 call 0x36ef862
13: 65 66 8b 05 47 43 c4 mov %gs:0x7ec44347(%rip),%ax # 0x7ec44362
1a: 7e
1b: 66 85 c0 test %ax,%ax
1e: 75 22 jne 0x42
20: bf 01 00 00 00 mov $0x1,%edi
25: e8 08 98 08 00 call 0x89832
* 2a: 65 8b 05 b9 40 c3 7e mov %gs:0x7ec340b9(%rip),%eax # 0x7ec340ea <-- trapping instruction
31: 85 c0 test %eax,%eax
33: 74 02 je 0x37
35: 5d pop %rbp
36: c3 ret
37: e8 5a 4c c1 ff call 0xffc14c96
3c: 5d pop %rbp
3d: c3 ret
3e: 0f 0b ud2