==================================================================
BUG: KASAN: use-after-free in rcu_cblist_dequeue+0x6c/0xb0 kernel/rcu/rcu_segcblist.c:75
Read of size 8 at addr ffff888112327990 by task syz.6.1282/4320
CPU: 1 PID: 4320 Comm: syz.6.1282 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:__sanitizer_cov_trace_pc+0x42/0x60 kernel/kcov.c:202
Code: c2 00 01 ff 00 74 11 f7 c2 00 01 00 00 74 35 83 b9 dc 0a 00 00 00 74 2c 8b 91 b8 0a 00 00 83 fa 02 75 21 48 8b 91 c0 0a 00 00 <48> 8b 32 48 8d 7e 01 8b 89 bc 0a 00 00 48 39 cf 73 08 48 89 44 f2
RSP: 0018:ffffc90000c76da0 EFLAGS: 00000246
RAX: ffffffff81717360 RBX: 0000000000000000 RCX: ffff88811bfc13c0
RDX: ffffc90001399000 RSI: ffffffff85406280 RDI: 0000000000000000
RBP: ffffc90000c76da0 R08: ffffc90000c76f10 R09: ffffc90000c76f08
R10: 000000000000000e R11: fffff5200018edd5 R12: dffffc0000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000001
is_bpf_text_address+0x20/0x190 kernel/bpf/core.c:721
kernel_text_address kernel/extable.c:151 [inline]
__kernel_text_address+0xa0/0x100 kernel/extable.c:105
unwind_get_return_address+0x4d/0x90 arch/x86/kernel/unwind_frame.c:19
arch_stack_walk+0xee/0x140 arch/x86/kernel/stacktrace.c:26
stack_trace_save+0xa6/0xf0 kernel/stacktrace.c:121
save_stack+0xc1/0x230 mm/page_owner.c:146
__set_page_owner+0x3b/0x2a0 mm/page_owner.c:219
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_pages include/linux/gfp.h:544 [inline]
__alloc_pages_node include/linux/gfp.h:557 [inline]
alloc_pages_node include/linux/gfp.h:571 [inline]
alloc_pages include/linux/gfp.h:590 [inline]
shmem_alloc_page+0x1fd/0x380 mm/shmem.c:1580
shmem_alloc_and_acct_page+0x3d3/0x840 mm/shmem.c:1605
shmem_getpage_gfp+0x785/0x20f0 mm/shmem.c:1918
shmem_getpage mm/shmem.c:161 [inline]
shmem_write_begin+0xce/0x1b0 mm/shmem.c:2497
generic_perform_write+0x2ce/0x540 mm/filemap.c:3509
__generic_file_write_iter+0x24b/0x480 mm/filemap.c:3638
generic_file_write_iter+0xa9/0x1d0 mm/filemap.c:3670
call_write_iter include/linux/fs.h:2066 [inline]
new_sync_write fs/read_write.c:518 [inline]
vfs_write+0x770/0xd70 fs/read_write.c:605
ksys_write+0x14a/0x260 fs/read_write.c:658
__do_sys_write fs/read_write.c:670 [inline]
__se_sys_write fs/read_write.c:667 [inline]
__x64_sys_write+0x7b/0x90 fs/read_write.c:667
do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x61/0xcb
RIP: 0033:0x7f1f4b9d290e
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:00007f1f4a46ada8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f1f4a46b6c0 RCX: 00007f1f4b9d290e
RDX: 00000000013bd7ef RSI: 00007f1f4204b000 RDI: 0000000000000003
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000003
R13: 00007f1f4a46aee0 R14: 00007f1f4a46aea0 R15: 00007f1f4204b000
Allocated by task 4331:
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:172
exit_to_user_mode_prepare+0x76/0xa0 kernel/entry/common.c:199
syscall_exit_to_user_mode+0x1d/0x40 kernel/entry/common.c:274
do_syscall_64+0x3d/0x40 arch/x86/entry/common.c:56
entry_SYSCALL_64_after_hwframe+0x61/0xcb
Second to 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
inetdev_destroy net/ipv4/devinet.c:330 [inline]
inetdev_event+0x825/0x1010 net/ipv4/devinet.c:1612
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 net/core/dev.c:2078 [inline]
unregister_netdevice_many+0x100e/0x19f0 net/core/dev.c:10778
vti6_exit_batch_net+0x273/0x2c0 net/ipv6/ip6_vti.c:1198
ops_exit_list net/core/net_namespace.c:190 [inline]
cleanup_net+0x5fe/0xb80 net/core/net_namespace.c:609
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
The buggy address belongs to the object at ffff888112327800
which belongs to the cache kmalloc-512 of size 512
The buggy address is located 400 bytes inside of
512-byte region [ffff888112327800, ffff888112327a00)
The buggy address belongs to the page:
page:ffffea000448c900 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x112324
head:ffffea000448c900 order:2 compound_mapcount:0 compound_pincount:0
flags: 0x4000000000010200(slab|head)
raw: 4000000000010200 ffffea0004985500 0000000200000002 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 106, ts 5539537479, free_ts 0
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]
alloc_uevent_skb+0x85/0x240 lib/kobject_uevent.c:290
uevent_net_broadcast_untagged lib/kobject_uevent.c:326 [inline]
kobject_uevent_net_broadcast+0x335/0x5a0 lib/kobject_uevent.c:409
kobject_uevent_env+0x52b/0x700 lib/kobject_uevent.c:608
kobject_synth_uevent+0x452/0x940 lib/kobject_uevent.c:208
uevent_store+0x25/0x60 drivers/base/core.c:2320
dev_attr_store+0x5e/0x80 drivers/base/core.c:2018
sysfs_kf_write+0x129/0x150 fs/sysfs/file.c:139
kernfs_fop_write_iter+0x2bd/0x400 fs/kernfs/file.c:296
page_owner free stack trace missing
Memory state around the buggy address:
ffff888112327880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888112327900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888112327980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff888112327a00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff888112327a80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================
----------------
Code disassembly (best guess):
0: c2 00 01 ret $0x100
3: ff 00 incl (%rax)
5: 74 11 je 0x18
7: f7 c2 00 01 00 00 test $0x100,%edx
d: 74 35 je 0x44
f: 83 b9 dc 0a 00 00 00 cmpl $0x0,0xadc(%rcx)
16: 74 2c je 0x44
18: 8b 91 b8 0a 00 00 mov 0xab8(%rcx),%edx
1e: 83 fa 02 cmp $0x2,%edx
21: 75 21 jne 0x44
23: 48 8b 91 c0 0a 00 00 mov 0xac0(%rcx),%rdx
* 2a: 48 8b 32 mov (%rdx),%rsi <-- trapping instruction
2d: 48 8d 7e 01 lea 0x1(%rsi),%rdi
31: 8b 89 bc 0a 00 00 mov 0xabc(%rcx),%ecx
37: 48 39 cf cmp %rcx,%rdi
3a: 73 08 jae 0x44
3c: 48 rex.W
3d: 89 .byte 0x89
3e: 44 rex.R
3f: f2 repnz