==================================================================
BUG: KASAN: use-after-free in rcu_cblist_dequeue+0x6c/0xb0 kernel/rcu/rcu_segcblist.c:75
Read of size 8 at addr ffff88814fe7c190 by task syz.1.1277/4510
CPU: 0 PID: 4510 Comm: syz.1.1277 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:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:161 [inline]
RIP: 0010:_raw_spin_unlock_irqrestore+0x56/0x80 kernel/locking/spinlock.c:194
Code: 47 6d 86 e8 6c 71 f5 fc 4c 89 f7 48 83 3d e9 90 b9 01 00 74 31 e8 ae 3c 9c fc 66 90 f7 c3 00 02 00 00 74 01 fb bf 01 00 00 00 65 0e 94 fc 65 8b 05 16 b7 4e 7b 85 c0 74 05 5b 41 5e 5d c3 e8
RSP: 0018:ffffc90000c475e0 EFLAGS: 00000206
RAX: 0000000000000001 RBX: 0000000000000a02 RCX: dffffc0000000000
RDX: ffffc90000d176d8 RSI: 0000000000000a02 RDI: 0000000000000001
RBP: ffffc90000c475f0 R08: ffff88811e330007 R09: 1ffff11023c66000
R10: dffffc0000000000 R11: ffffed1023c66001 R12: ffff888118986900
R13: 0000000000000010 R14: 0000000000000001 R15: 0000000000000000
spin_unlock_irqrestore include/linux/spinlock.h:419 [inline]
__wake_up_common_lock kernel/sched/wait.c:141 [inline]
__wake_up_sync_key+0x17b/0x2b0 kernel/sched/wait.c:209
__unix_dgram_recvmsg+0x4af/0xd50 net/unix/af_unix.c:2349
unix_dgram_recvmsg+0xc2/0xe0 net/unix/af_unix.c:2420
____sys_recvmsg+0x2ca/0x5b0 net/socket.c:-1
___sys_recvmsg+0x213/0x5c0 net/socket.c:2697
do_recvmmsg+0x360/0x7d0 net/socket.c:2791
__sys_recvmmsg net/socket.c:2870 [inline]
__do_sys_recvmmsg net/socket.c:2893 [inline]
__se_sys_recvmmsg net/socket.c:2886 [inline]
__x64_sys_recvmmsg+0x195/0x250 net/socket.c:2886
x64_sys_call+0x297/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:300
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: 0033:0x7f2a03157e59
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:00007f2a01b90028 EFLAGS: 00000246 ORIG_RAX: 000000000000012b
RAX: ffffffffffffffda RBX: 00007f2a033e0090 RCX: 00007f2a03157e59
RDX: 0000000000010106 RSI: 00002000000000c0 RDI: 0000000000000003
RBP: 00007f2a031ede6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000002 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f2a033e0128 R14: 00007f2a033e0090 R15: 00007ffe47daaa48
Allocated by task 4479:
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 10:
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
get_signal+0x13b1/0x1430 kernel/signal.c:2680
arch_do_signal_or_restart+0xe2/0x1100 arch/x86/kernel/signal.c:867
handle_signal_work kernel/entry/common.c:154 [inline]
exit_to_user_mode_loop+0xa7/0xe0 kernel/entry/common.c:178
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 ffff88814fe7c000
which belongs to the cache kmalloc-512 of size 512
The buggy address is located 400 bytes inside of
512-byte region [ffff88814fe7c000, ffff88814fe7c200)
The buggy address belongs to the page:
page:ffffea00053f9f00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x14fe7c
head:ffffea00053f9f00 order:2 compound_mapcount:0 compound_pincount:0
flags: 0x4000000000010200(slab|head|zone=1)
raw: 4000000000010200 ffffea0004a3ca00 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 0x1d2a20(GFP_ATOMIC|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_HARDWALL), pid 3088, ts 125228424568, 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]
pskb_expand_head+0x123/0x1280 net/core/skbuff.c:1734
skb_ensure_writable+0x2e0/0x460 net/core/skbuff.c:5824
__bpf_try_make_writable net/core/filter.c:1676 [inline]
bpf_try_make_writable net/core/filter.c:1682 [inline]
bpf_try_make_head_writable net/core/filter.c:1690 [inline]
____bpf_clone_redirect net/core/filter.c:2465 [inline]
bpf_clone_redirect+0x1c6/0x460 net/core/filter.c:2434
0xffffffffa0034b1a
bpf_dispatcher_nop_func include/linux/bpf.h:785 [inline]
__bpf_prog_run include/linux/filter.h:628 [inline]
bpf_prog_run include/linux/filter.h:635 [inline]
bpf_test_run+0x351/0x900 net/bpf/test_run.c:119
bpf_prog_test_run_skb+0xa0c/0x1180 net/bpf/test_run.c:678
bpf_prog_test_run+0x3a5/0x5b0 kernel/bpf/syscall.c:3348
__sys_bpf+0x590/0x7d0 kernel/bpf/syscall.c:4651
page_owner free stack trace missing
Memory state around the buggy address:
ffff88814fe7c080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88814fe7c100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88814fe7c180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff88814fe7c200: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff88814fe7c280: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================
----------------
Code disassembly (best guess):
0: 47 6d rex.RXB insl (%dx),%es:(%rdi)
2: 86 e8 xchg %ch,%al
4: 6c insb (%dx),%es:(%rdi)
5: 71 f5 jno 0xfffffffc
7: fc cld
8: 4c 89 f7 mov %r14,%rdi
b: 48 83 3d e9 90 b9 01 cmpq $0x0,0x1b990e9(%rip) # 0x1b990fc
12: 00
13: 74 31 je 0x46
15: e8 ae 3c 9c fc call 0xfc9c3cc8
1a: 66 90 xchg %ax,%ax
1c: f7 c3 00 02 00 00 test $0x200,%ebx
22: 74 01 je 0x25
24: fb sti
25: bf 01 00 00 00 mov $0x1,%edi
* 2a: e8 65 0e 94 fc call 0xfc940e94 <-- trapping instruction
2f: 65 8b 05 16 b7 4e 7b mov %gs:0x7b4eb716(%rip),%eax # 0x7b4eb74c
36: 85 c0 test %eax,%eax
38: 74 05 je 0x3f
3a: 5b pop %rbx
3b: 41 5e pop %r14
3d: 5d pop %rbp
3e: c3 ret
3f: e8 .byte 0xe8