==================================================================
BUG: KASAN: use-after-free in rcu_cblist_dequeue+0x6c/0xb0 kernel/rcu/rcu_segcblist.c:75
Read of size 8 at addr ffff888130d9f190 by task syz-executor/2497
CPU: 0 PID: 2497 Comm: syz-executor Tainted: G W 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:do_slab_free mm/slub.c:3666 [inline]
RIP: 0010:___cache_free+0xba/0xd0 mm/slub.c:3722
Code: f2 4c 89 14 19 48 8d 4a 08 4c 8b 17 65 49 0f c7 0a 0f 94 c0 a8 01 74 b5 5b 5d c3 4c 89 c6 48 89 da 48 89 d9 41 b8 01 00 00 00 e1 38 00 00 eb e7 48 ff c9 48 89 c8 eb 86 0f 0b 0f 1f 44 00 00
RSP: 0018:ffffc90002a07b90 EFLAGS: 00000202
RAX: ffff8881f6e3b6f0 RBX: ffff88811eb4fb80 RCX: ffff88811eb4fb80
RDX: ffff88811eb4fb80 RSI: ffffea00047ad3c0 RDI: ffff888100042600
RBP: ffffc90002a07b98 R08: 0000000000000001 R09: ffffffff81b71dab
R10: 000000000003cf40 R11: fffff52000540f3c R12: ffff888100042600
R13: dffffc0000000000 R14: 0000000000000000 R15: ffff88811eb4fb80
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]
slab_alloc mm/slub.c:3392 [inline]
__kmem_cache_alloc_lru mm/slub.c:3399 [inline]
kmem_cache_alloc+0x166/0x320 mm/slub.c:3408
getname_flags+0xba/0x510 fs/namei.c:139
getname+0x19/0x20 fs/namei.c:218
do_sys_openat2+0xeb/0x820 fs/open.c:1337
do_sys_open fs/open.c:1359 [inline]
__do_sys_openat fs/open.c:1375 [inline]
__se_sys_openat fs/open.c:1370 [inline]
__x64_sys_openat+0x136/0x160 fs/open.c:1370
x64_sys_call+0x783/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:258
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: 0033:0x7ff29879ee3c
Code: 4c 89 54 24 18 41 89 f2 41 83 e2 40 75 40 89 f0 f7 d0 a9 00 00 41 00 74 35 89 f2 b8 01 01 00 00 48 89 fe bf 9c ff ff ff 0f 05 <48> 3d 00 f0 ff ff 77 44 48 8b 54 24 18 64 48 2b 14 25 28 00 00 00
RSP: 002b:00007ffef8ba7a60 EFLAGS: 00000206 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007ff298836fb3 RCX: 00007ff29879ee3c
RDX: 0000000000090800 RSI: 00007ffef8ba8c10 RDI: 00000000ffffff9c
RBP: 00007ffef8ba8bfc R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000206 R12: 00007ffef8ba8c10
R13: 00007ff298836fb3 R14: 00000000000ac875 R15: 00007ffef8ba8c50
Allocated by task 9674:
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 1222:
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_sys_exit kernel/exit.c:1006 [inline]
__se_sys_exit kernel/exit.c:1004 [inline]
__cfi___ia32_sys_exit+0x0/0x10 kernel/exit.c:1004
x64_sys_call+0x67/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:61
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
The buggy address belongs to the object at ffff888130d9f000
which belongs to the cache kmalloc-512 of size 512
The buggy address is located 400 bytes inside of
512-byte region [ffff888130d9f000, ffff888130d9f200)
The buggy address belongs to the physical page:
page:ffffea0004c36700 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x130d9c
head:ffffea0004c36700 order:2 compound_mapcount:0 compound_pincount:0
flags: 0x4000000000010200(slab|head|zone=1)
raw: 4000000000010200 0000000000000000 dead000000000122 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 9668, tgid 9668 (syz.5.2732), ts 705383330891, free_ts 702436878628
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+0xa4/0x1e0 mm/slab_common.c:951
kmalloc include/linux/slab.h:568 [inline]
kzalloc include/linux/slab.h:699 [inline]
neigh_alloc net/core/neighbour.c:494 [inline]
___neigh_create+0x6e3/0x1db0 net/core/neighbour.c:648
__neigh_create+0x31/0x40 net/core/neighbour.c:737
ip6_finish_output2+0xaaf/0x18b0 net/ipv6/ip6_output.c:129
__ip6_finish_output net/ipv6/ip6_output.c:205 [inline]
ip6_finish_output+0x60b/0xbe0 net/ipv6/ip6_output.c:216
NF_HOOK_COND include/linux/netfilter.h:294 [inline]
ip6_output+0x1fa/0x410 net/ipv6/ip6_output.c:237
dst_output include/net/dst.h:453 [inline]
NF_HOOK include/linux/netfilter.h:305 [inline]
ndisc_send_skb+0x7c8/0xcd0 net/ipv6/ndisc.c:513
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_large_kmalloc+0xae/0xf0 mm/slab_common.c:915
kfree+0x8b/0xf0 mm/slab_common.c:984
kvfree+0x35/0x40 mm/util.c:639
bpf_check+0xd733/0x10e90 kernel/bpf/verifier.c:15705
bpf_prog_load+0x10f4/0x1670 kernel/bpf/syscall.c:2624
__sys_bpf+0x57b/0x850 kernel/bpf/syscall.c:5006
__do_sys_bpf kernel/bpf/syscall.c:5110 [inline]
__se_sys_bpf kernel/bpf/syscall.c:5108 [inline]
__x64_sys_bpf+0x7c/0x90 kernel/bpf/syscall.c:5108
x64_sys_call+0x488/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:322
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
Memory state around the buggy address:
ffff888130d9f080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888130d9f100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888130d9f180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff888130d9f200: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff888130d9f280: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================
----------------
Code disassembly (best guess):
0: f2 4c 89 14 19 repnz mov %r10,(%rcx,%rbx,1)
5: 48 8d 4a 08 lea 0x8(%rdx),%rcx
9: 4c 8b 17 mov (%rdi),%r10
c: 65 49 0f c7 0a cmpxchg16b %gs:(%r10)
11: 0f 94 c0 sete %al
14: a8 01 test $0x1,%al
16: 74 b5 je 0xffffffcd
18: 5b pop %rbx
19: 5d pop %rbp
1a: c3 ret
1b: 4c 89 c6 mov %r8,%rsi
1e: 48 89 da mov %rbx,%rdx
21: 48 89 d9 mov %rbx,%rcx
24: 41 b8 01 00 00 00 mov $0x1,%r8d
* 2a: e8 e1 38 00 00 call 0x3910 <-- trapping instruction
2f: eb e7 jmp 0x18
31: 48 ff c9 dec %rcx
34: 48 89 c8 mov %rcx,%rax
37: eb 86 jmp 0xffffffbf
39: 0f 0b ud2
3b: 0f 1f 44 00 00 nopl 0x0(%rax,%rax,1)