==================================================================
BUG: KASAN: use-after-free in rcu_cblist_dequeue+0x6c/0xb0 kernel/rcu/rcu_segcblist.c:75
Read of size 8 at addr ffff88811017c190 by task syz.0.342/1671
CPU: 0 PID: 1671 Comm: syz.0.342 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:console_emit_next_record+0x87e/0xa80 kernel/printk/printk.c:2797
Code: de 48 81 e6 00 02 00 00 31 ff e8 dd 82 19 00 48 81 e3 00 02 00 00 75 07 e8 0f 7e 19 00 eb 06 e8 08 7e 19 00 fb 0f b6 5c 24 17 <66> 43 c7 44 2f 20 f8 f8 43 c6 44 2f 22 f8 4f 89 74 2f 10 66 43 c7
RSP: 0018:ffffc90000f27640 EFLAGS: 00000283
RAX: ffffffff8157e628 RBX: 0000000000000001 RCX: 0000000000080000
RDX: ffffc900012b9000 RSI: 0000000000001fe9 RDI: 0000000000001fea
RBP: ffffc90000f27830 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffff520001e4eb8 R12: ffffc90000f2787f
R13: dffffc0000000000 R14: f8f8f8f8f8f8f8f8 R15: 1ffff920001e4ed4
console_flush_all kernel/printk/printk.c:-1 [inline]
console_unlock+0x246/0x560 kernel/printk/printk.c:2917
vprintk_emit+0x14d/0x420 kernel/printk/printk.c:2308
vprintk_default+0x26/0x30 kernel/printk/printk.c:2323
vprintk+0x7a/0x80 kernel/printk/printk_safe.c:45
_printk+0xda/0x128 kernel/printk/printk.c:2333
usb_gadget_register_driver_owner+0x20d/0x270 drivers/usb/gadget/udc/core.c:1682
raw_ioctl_run drivers/usb/gadget/legacy/raw_gadget.c:549 [inline]
raw_ioctl+0x112c/0x3180 drivers/usb/gadget/legacy/raw_gadget.c:1262
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:870 [inline]
__se_sys_ioctl+0x12f/0x1b0 fs/ioctl.c:856
__x64_sys_ioctl+0x7b/0x90 fs/ioctl.c:856
x64_sys_call+0x58b/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:17
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: 0033:0x7f1961d9caeb
Code: 00 48 89 44 24 18 31 c0 48 8d 44 24 60 c7 04 24 10 00 00 00 48 89 44 24 08 48 8d 44 24 20 48 89 44 24 10 b8 10 00 00 00 0f 05 <89> c2 3d 00 f0 ff ff 77 1c 48 8b 44 24 18 64 48 2b 04 25 28 00 00
RSP: 002b:00007f1962c86f00 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 00007f1961d9caeb
RDX: 0000000000000000 RSI: 0000000000005501 RDI: 0000000000000005
RBP: 00007f1962c87fd0 R08: 0000000000000001 R09: 00000000ffffffff
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000200000000000 R14: 0000000000000001 R15: 0000000000000868
Allocated by task 1677:
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 1480:
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
Second to 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
fib6_info_release include/net/ip6_fib.h:350 [inline]
ip6_route_info_create+0xaa8/0x14d0 net/ipv6/route.c:3878
ip6_route_add+0x27/0x130 net/ipv6/route.c:3892
addrconf_prefix_route+0x233/0x310 net/ipv6/addrconf.c:2466
inet6_addr_add+0x527/0x9c0 net/ipv6/addrconf.c:3042
inet6_rtm_newaddr+0x74a/0xa10 net/ipv6/addrconf.c:4999
rtnetlink_rcv_msg+0xb28/0xde0 net/core/rtnetlink.c:6153
netlink_rcv_skb+0x200/0x450 net/netlink/af_netlink.c:2521
rtnetlink_rcv+0x1c/0x20 net/core/rtnetlink.c:6171
netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline]
netlink_unicast+0x8c1/0xa60 net/netlink/af_netlink.c:1345
netlink_sendmsg+0x8b9/0xbd0 net/netlink/af_netlink.c:1873
sock_sendmsg_nosec net/socket.c:716 [inline]
__sock_sendmsg net/socket.c:728 [inline]
__sys_sendto+0x4ac/0x660 net/socket.c:2142
__do_sys_sendto net/socket.c:2154 [inline]
__se_sys_sendto net/socket.c:2150 [inline]
__x64_sys_sendto+0xe5/0x100 net/socket.c:2150
x64_sys_call+0x83/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:45
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 ffff88811017c000
which belongs to the cache kmalloc-512 of size 512
The buggy address is located 400 bytes inside of
512-byte region [ffff88811017c000, ffff88811017c200)
The buggy address belongs to the physical page:
page:ffffea0004405f00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x11017c
head:ffffea0004405f00 order:2 compound_mapcount:0 compound_pincount:0
flags: 0x4000000000010200(slab|head|zone=1)
raw: 4000000000010200 0000000000000000 dead000000000001 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 91, tgid 91 (klogd), ts 6608071323, free_ts 0
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]
alloc_skb_with_frags+0xa8/0x620 net/core/skbuff.c:6176
sock_alloc_send_pskb+0x87f/0x9a0 net/core/sock.c:2761
unix_dgram_sendmsg+0x5c1/0x1710 net/unix/af_unix.c:1947
sock_sendmsg_nosec net/socket.c:716 [inline]
__sock_sendmsg net/socket.c:728 [inline]
__sys_sendto+0x4ac/0x660 net/socket.c:2142
__do_sys_sendto net/socket.c:2154 [inline]
__se_sys_sendto net/socket.c:2150 [inline]
__x64_sys_sendto+0xe5/0x100 net/socket.c:2150
page_owner free stack trace missing
Memory state around the buggy address:
ffff88811017c080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88811017c100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88811017c180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff88811017c200: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff88811017c280: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================
----------------
Code disassembly (best guess):
0: de 48 81 fimuls -0x7f(%rax)
3: e6 00 out %al,$0x0
5: 02 00 add (%rax),%al
7: 00 31 add %dh,(%rcx)
9: ff ljmp (bad)
a: e8 dd 82 19 00 call 0x1982ec
f: 48 81 e3 00 02 00 00 and $0x200,%rbx
16: 75 07 jne 0x1f
18: e8 0f 7e 19 00 call 0x197e2c
1d: eb 06 jmp 0x25
1f: e8 08 7e 19 00 call 0x197e2c
24: fb sti
25: 0f b6 5c 24 17 movzbl 0x17(%rsp),%ebx
* 2a: 66 43 c7 44 2f 20 f8 movw $0xf8f8,0x20(%r15,%r13,1) <-- trapping instruction
31: f8
32: 43 c6 44 2f 22 f8 movb $0xf8,0x22(%r15,%r13,1)
38: 4f 89 74 2f 10 mov %r14,0x10(%r15,%r13,1)
3d: 66 data16
3e: 43 rex.XB
3f: c7 .byte 0xc7