==================================================================
BUG: KASAN: use-after-free in rcu_cblist_dequeue+0x6c/0xb0 kernel/rcu/rcu_segcblist.c:75
Read of size 8 at addr ffff888130d84990 by task syz.4.5731/20504
CPU: 1 PID: 20504 Comm: syz.4.5731 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
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+0x1d7/0x600 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:vm_normal_page+0x99/0x200 mm/memory.c:691
Code: 89 f0 48 25 00 02 00 00 75 40 4c 8b 2d b8 28 e8 05 4c 89 e7 4c 89 ee e8 d5 a0 c6 ff 4d 39 ec 0f 87 9e 00 00 00 e8 77 9e c6 ff <49> c1 e4 06 48 b8 00 00 00 00 00 ea ff ff 4c 01 e0 48 83 c4 08 5b
RSP: 0018:ffffc90000d072c0 EFLAGS: 00000293
RAX: ffffffff81aab6a9 RBX: 000020000032d000 RCX: ffff88812968d100
RDX: 0000000000000000 RSI: 000000000023ffff RDI: 00000000001350c6
RBP: ffffc90000d072f0 R08: ffff88812968d107 R09: 1ffff110252d1a20
R10: dffffc0000000000 R11: ffffed10252d1a21 R12: 00000000001350c6
R13: 000000000023ffff R14: 80000001350c6027 R15: ffff88814d4f1318
zap_pte_range mm/memory.c:1454 [inline]
zap_pmd_range mm/memory.c:1599 [inline]
zap_pud_range mm/memory.c:1628 [inline]
zap_p4d_range mm/memory.c:1649 [inline]
unmap_page_range+0xc4d/0x2360 mm/memory.c:1670
unmap_single_vma mm/memory.c:1716 [inline]
unmap_vmas+0x34c/0x480 mm/memory.c:1756
unmap_region+0x221/0x320 mm/mmap.c:2415
do_mas_align_munmap+0xbf3/0x1330 mm/mmap.c:2693
do_mas_munmap+0x23d/0x2b0 mm/mmap.c:2751
__mmap_region mm/mmap.c:2799 [inline]
mmap_region+0x89e/0x2130 mm/mmap.c:3030
do_mmap+0x858/0xdd0 mm/mmap.c:1491
vm_mmap_pgoff+0x206/0x3f0 mm/util.c:525
ksys_mmap_pgoff+0xf6/0x1d0 mm/mmap.c:1537
__do_sys_mmap arch/x86/kernel/sys_x86_64.c:93 [inline]
__se_sys_mmap arch/x86/kernel/sys_x86_64.c:86 [inline]
__x64_sys_mmap+0xfa/0x110 arch/x86/kernel/sys_x86_64.c:86
x64_sys_call+0x8fd/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:10
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: 0033:0x7f3ee639ce59
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:00007f3ee71c3028 EFLAGS: 00000246 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 00007f3ee6616180 RCX: 00007f3ee639ce59
RDX: b635773f06ebbeeb RSI: 0000000000b36000 RDI: 0000200000000000
RBP: 00007f3ee6432e6f R08: ffffffffffffffff R09: 0000000000000000
R10: 0000000000008031 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f3ee6616218 R14: 00007f3ee6616180 R15: 00007ffc29cd6b58
Allocated by task 20510:
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:1609
pppol2tp_connect+0xbf5/0x1640 net/l2tp/l2tp_ppp.c:771
__sys_connect_file net/socket.c:2000 [inline]
__sys_connect+0x3da/0x460 net/socket.c:2017
__do_sys_connect net/socket.c:2027 [inline]
__se_sys_connect net/socket.c:2024 [inline]
__x64_sys_connect+0x7a/0x90 net/socket.c:2024
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 10646:
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:1582
l2tp_tunnel_closeall net/l2tp/l2tp_core.c:1228 [inline]
l2tp_tunnel_del_work+0x199/0x410 net/l2tp/l2tp_core.c:1266
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:1389
__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
resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
exit_to_user_mode_loop+0x9b/0xb0 kernel/entry/common.c:177
exit_to_user_mode_prepare+0x87/0xd0 kernel/entry/common.c:210
__syscall_exit_to_user_mode_work kernel/entry/common.c:292 [inline]
syscall_exit_to_user_mode+0x1a/0x30 kernel/entry/common.c:303
do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:82
entry_SYSCALL_64_after_hwframe+0x68/0xd2
The buggy address belongs to the object at ffff888130d84800
which belongs to the cache kmalloc-512 of size 512
The buggy address is located 400 bytes inside of
512-byte region [ffff888130d84800, ffff888130d84a00)
The buggy address belongs to the physical page:
page:ffffea0004c36100 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x130d84
head:ffffea0004c36100 order:2 compound_mapcount:0 compound_pincount:0
flags: 0x4000000000010200(slab|head|zone=1)
raw: 4000000000010200 ffffea0004c96d00 dead000000000002 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 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 287, tgid 287 (syz-executor), ts 22976384184, free_ts 22971849999
set_page_owner include/linux/page_owner.h:33 [inline]
post_alloc_hook+0x1f5/0x210 mm/page_alloc.c:2672
prep_new_page+0x1c/0x110 mm/page_alloc.c:2679
get_page_from_freelist+0x2ca9/0x2d20 mm/page_alloc.c:4586
__alloc_pages+0x1fa/0x610 mm/page_alloc.c:5930
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_node_track_caller+0xa1/0x1e0 mm/slab_common.c:958
kmalloc_reserve net/core/skbuff.c:449 [inline]
__alloc_skb+0x226/0x4a0 net/core/skbuff.c:518
alloc_skb include/linux/skbuff.h:1322 [inline]
nlmsg_new include/net/netlink.h:987 [inline]
inet6_netconf_notify_devconf+0x107/0x1c0 net/ipv6/addrconf.c:586
__addrconf_sysctl_register+0x36e/0x3e0 net/ipv6/addrconf.c:7202
addrconf_sysctl_register+0x147/0x1a0 net/ipv6/addrconf.c:7239
ipv6_add_dev+0xbf5/0x1130 net/ipv6/addrconf.c:455
addrconf_notify+0x6d0/0xe30 net/ipv6/addrconf.c:3621
page last free stack trace:
reset_page_owner include/linux/page_owner.h:26 [inline]
free_pages_prepare mm/page_alloc.c:1580 [inline]
free_pcp_prepare mm/page_alloc.c:1654 [inline]
free_unref_page_prepare+0x80c/0x820 mm/page_alloc.c:3621
free_unref_page+0x93/0x530 mm/page_alloc.c:3719
free_the_page mm/page_alloc.c:863 [inline]
__free_pages+0x67/0x100 mm/page_alloc.c:6020
free_pages+0x82/0x90 mm/page_alloc.c:6031
__stack_depot_save+0x45f/0x490 lib/stackdepot.c:506
kasan_save_stack mm/kasan/common.c:47 [inline]
kasan_set_track+0x60/0x70 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_node_track_caller+0xb1/0x1e0 mm/slab_common.c:958
kmemdup+0x2b/0x60 mm/util.c:134
kmemdup include/linux/fortify-string.h:585 [inline]
neigh_sysctl_register+0xbf/0xa80 net/core/neighbour.c:3790
addrconf_sysctl_register+0xb3/0x1a0 net/ipv6/addrconf.c:7235
ipv6_add_dev+0xbf5/0x1130 net/ipv6/addrconf.c:455
addrconf_notify+0x6d0/0xe30 net/ipv6/addrconf.c:3621
notifier_call_chain kernel/notifier.c:87 [inline]
raw_notifier_call_chain+0xa1/0x110 kernel/notifier.c:455
call_netdevice_notifiers_info net/core/dev.c:2022 [inline]
call_netdevice_notifiers_extack net/core/dev.c:2060 [inline]
call_netdevice_notifiers+0x119/0x190 net/core/dev.c:2074
Memory state around the buggy address:
ffff888130d84880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888130d84900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888130d84980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff888130d84a00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff888130d84a80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================
ip6_tunnel: ip6tnl1 xmit: Local address not yet configured!
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0)
----------------
Code disassembly (best guess):
0: 89 f0 mov %esi,%eax
2: 48 25 00 02 00 00 and $0x200,%rax
8: 75 40 jne 0x4a
a: 4c 8b 2d b8 28 e8 05 mov 0x5e828b8(%rip),%r13 # 0x5e828c9
11: 4c 89 e7 mov %r12,%rdi
14: 4c 89 ee mov %r13,%rsi
17: e8 d5 a0 c6 ff call 0xffc6a0f1
1c: 4d 39 ec cmp %r13,%r12
1f: 0f 87 9e 00 00 00 ja 0xc3
25: e8 77 9e c6 ff call 0xffc69ea1
* 2a: 49 c1 e4 06 shl $0x6,%r12 <-- trapping instruction
2e: 48 b8 00 00 00 00 00 movabs $0xffffea0000000000,%rax
35: ea ff ff
38: 4c 01 e0 add %r12,%rax
3b: 48 83 c4 08 add $0x8,%rsp
3f: 5b pop %rbx