==================================================================
BUG: KASAN: use-after-free in rcu_segcblist_restempty kernel/rcu/rcu_segcblist.h:110 [inline]
BUG: KASAN: use-after-free in rcu_segcblist_accelerate+0x1e7/0x420 kernel/rcu/rcu_segcblist.c:581
Read of size 8 at addr ffff88810f83ad90 by task syz.7.274/1413
CPU: 1 PID: 1413 Comm: syz.7.274 Tainted: G W 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_segcblist_restempty kernel/rcu/rcu_segcblist.h:110 [inline]
rcu_segcblist_accelerate+0x1e7/0x420 kernel/rcu/rcu_segcblist.c:581
rcu_accelerate_cbs kernel/rcu/tree.c:1521 [inline]
rcu_report_qs_rdp kernel/rcu/tree.c:2326 [inline]
rcu_check_quiescent_state kernel/rcu/tree.c:2366 [inline]
rcu_core+0x7d2/0xef0 kernel/rcu/tree.c:2747
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:unwind_get_return_address+0x56/0x90 arch/x86/kernel/unwind_frame.c:19
Code: 83 c3 48 49 89 df 49 c1 ef 03 43 80 3c 37 00 74 08 48 89 df e8 9b 6d 77 00 48 8b 3b e8 f3 84 13 00 85 c0 74 14 43 80 3c 37 00 <74> 08 48 89 df e8 80 6d 77 00 48 8b 03 eb 02 31 c0 5b 41 5e 41 5f
RSP: 0000:ffffc900012371e0 EFLAGS: 00000246
RAX: 0000000000000001 RBX: ffffc90001237250 RCX: 0000000000246e01
RDX: ffffc90001237cb0 RSI: 1ffff92000246e42 RDI: ffffffff81320ec8
RBP: ffffc900012371f8 R08: ffffc900012372d0 R09: ffffc900012372c8
R10: 0000000000000006 R11: fffff52000246e4d R12: ffff8881106e2780
R13: 1ffff110220dc5a2 R14: dffffc0000000000 R15: 1ffff92000246e4a
arch_stack_walk+0xee/0x140 arch/x86/kernel/stacktrace.c:26
stack_trace_save+0xa6/0xf0 kernel/stacktrace.c:122
save_stack+0x121/0x230 mm/page_owner.c:139
__set_page_owner+0x2b/0x2e0 mm/page_owner.c:200
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_pages_node include/linux/gfp.h:595 [inline]
alloc_pages_node include/linux/gfp.h:609 [inline]
alloc_pages include/linux/gfp.h:622 [inline]
__pte_alloc_one include/asm-generic/pgalloc.h:63 [inline]
pte_alloc_one+0x70/0x190 arch/x86/mm/pgtable.c:33
do_fault_around mm/memory.c:4519 [inline]
do_read_fault mm/memory.c:4561 [inline]
do_fault mm/memory.c:4709 [inline]
handle_pte_fault+0x19d0/0x2770 mm/memory.c:4923
__handle_mm_fault mm/memory.c:-1 [inline]
do_handle_mm_fault+0x1b3b/0x1e30 mm/memory.c:5345
handle_mm_fault include/linux/mm.h:1847 [inline]
do_user_addr_fault+0x808/0x11c0 arch/x86/mm/fault.c:1416
handle_page_fault arch/x86/mm/fault.c:1507 [inline]
exc_page_fault+0x51/0xb0 arch/x86/mm/fault.c:1560
asm_exc_page_fault+0x27/0x30 arch/x86/include/asm/idtentry.h:606
RIP: 0033:0x7f8231d03615
Code: ff 0f 1f 40 00 53 48 8b 1d a8 27 3c 00 45 31 d2 31 c9 48 8b 17 45 31 db 4c 8d 83 00 00 40 00 48 89 d0 0f 1f 00 4c 39 c0 73 63 <44> 0f b6 08 48 83 c0 01 4c 89 ce 83 e6 7f 48 d3 e6 49 09 f2 45 84
RSP: 002b:00007ffce7c0e080 EFLAGS: 00010287
RAX: 0000001b33b20000 RBX: 0000001b33b20000 RCX: 0000000000000000
RDX: 0000001b33b20000 RSI: 00007ffce7c0e070 RDI: 00007ffce7c0e170
RBP: 00000000000167ff R08: 0000001b33f20000 R09: 00088c65d8ba4030
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: 00000000000167ff R15: 00007ffce7c0e320
Allocated by task 1412:
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:1922 [inline]
__sys_connect+0x3cb/0x450 net/socket.c:1939
__do_sys_connect net/socket.c:1949 [inline]
__se_sys_connect net/socket.c:1946 [inline]
__x64_sys_connect+0x7a/0x90 net/socket.c:1946
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 370:
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:1335
__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 ffff88810f83ac00
which belongs to the cache kmalloc-512 of size 512
The buggy address is located 400 bytes inside of
512-byte region [ffff88810f83ac00, ffff88810f83ae00)
The buggy address belongs to the page:
page:ffffea00043e0e00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x10f838
head:ffffea00043e0e00 order:2 compound_mapcount:0 compound_pincount:0
flags: 0x4000000000010200(slab|head|zone=1)
raw: 4000000000010200 ffffea00043fb500 0000000200000002 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 102, ts 4065377159, 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_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+0x457/0x940 lib/kobject_uevent.c:208
uevent_store+0x4b/0x70 drivers/base/bus.c:583
drv_attr_store+0x79/0xa0 drivers/base/bus.c:77
sysfs_kf_write+0x129/0x150 fs/sysfs/file.c:139
page_owner free stack trace missing
Memory state around the buggy address:
ffff88810f83ac80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88810f83ad00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88810f83ad80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff88810f83ae00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff88810f83ae80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================
----------------
Code disassembly (best guess):
0: 83 c3 48 add $0x48,%ebx
3: 49 89 df mov %rbx,%r15
6: 49 c1 ef 03 shr $0x3,%r15
a: 43 80 3c 37 00 cmpb $0x0,(%r15,%r14,1)
f: 74 08 je 0x19
11: 48 89 df mov %rbx,%rdi
14: e8 9b 6d 77 00 call 0x776db4
19: 48 8b 3b mov (%rbx),%rdi
1c: e8 f3 84 13 00 call 0x138514
21: 85 c0 test %eax,%eax
23: 74 14 je 0x39
25: 43 80 3c 37 00 cmpb $0x0,(%r15,%r14,1)
* 2a: 74 08 je 0x34 <-- trapping instruction
2c: 48 89 df mov %rbx,%rdi
2f: e8 80 6d 77 00 call 0x776db4
34: 48 8b 03 mov (%rbx),%rax
37: eb 02 jmp 0x3b
39: 31 c0 xor %eax,%eax
3b: 5b pop %rbx
3c: 41 5e pop %r14
3e: 41 5f pop %r15