==================================================================
BUG: KASAN: use-after-free in rcu_cblist_dequeue+0x6c/0xb0 kernel/rcu/rcu_segcblist.c:75
Read of size 8 at addr ffff88811bd27990 by task syz.9.1253/4875
CPU: 1 PID: 4875 Comm: syz.9.1253 Not tainted 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:native_restore_fl arch/x86/include/asm/irqflags.h:41 [inline]
RIP: 0010:arch_local_irq_restore arch/x86/include/asm/irqflags.h:84 [inline]
RIP: 0010:rmqueue_pcplist mm/page_alloc.c:3775 [inline]
RIP: 0010:rmqueue mm/page_alloc.c:3791 [inline]
RIP: 0010:get_page_from_freelist+0x22fd/0x23f0 mm/page_alloc.c:4251
Code: e8 68 25 04 00 4c 89 74 24 18 49 8b 06 48 c1 e8 3e 65 48 ff 04 c5 50 38 05 00 4c 89 a4 24 58 01 00 00 ff b4 24 58 01 00 00 9d 01 89 84 24 94 00 00 00 44 8b 3c 24 e9 98 fe ff ff 4c 89 f7 48
RSP: 0018:ffffc90000ff6e40 EFLAGS: 00000246
RAX: 0000000000000001 RBX: ffffea0004bf1ac8 RCX: dffffc0000000000
RDX: ffffea0004bf1ac8 RSI: ffffffff8527a760 RDI: 00000000ffffffff
RBP: ffffc90000ff7030 R08: ffffffff8640d347 R09: 1ffffffff0c81a68
R10: dffffc0000000000 R11: fffffbfff0c81a69 R12: 0000000000000246
R13: ffff8881f715ab50 R14: ffffea0004bf1ac0 R15: ffffea0004bf1ad0
__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_fault+0x2b5/0x650 mm/shmem.c:2139
__do_fault mm/memory.c:4064 [inline]
do_read_fault mm/memory.c:4408 [inline]
do_fault mm/memory.c:4536 [inline]
handle_pte_fault+0x2466/0x3910 mm/memory.c:4800
__handle_mm_fault mm/memory.c:4953 [inline]
handle_mm_fault+0xf86/0x1720 mm/memory.c:5367
faultin_page mm/gup.c:902 [inline]
__get_user_pages+0xbf8/0x1400 mm/gup.c:1121
populate_vma_page_range mm/gup.c:1454 [inline]
__mm_populate+0x31c/0x420 mm/gup.c:1502
mm_populate include/linux/mm.h:2793 [inline]
vm_mmap_pgoff+0x23b/0x350 mm/util.c:548
ksys_mmap_pgoff+0xfd/0x1e0 mm/mmap.c:1712
__do_sys_mmap arch/x86/kernel/sys_x86_64.c:95 [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
do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x61/0xcb
RIP: 0033:0x7f06cbe300d9
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:00007f06ca889028 EFLAGS: 00000246 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 00007f06cc0b7fa0 RCX: 00007f06cbe300d9
RDX: b635773f066bbeeb RSI: 0000000000b36000 RDI: 0000200000000000
RBP: 00007f06cbec7024 R08: ffffffffffffffff R09: 0000000000000000
R10: 0000000000008031 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f06cc0b8038 R14: 00007f06cc0b7fa0 R15: 00007ffe0d3e10f8
Allocated by task 4778:
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 7:
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
exit_task_work include/linux/task_work.h:33 [inline]
do_exit+0xa7c/0x24e0 kernel/exit.c:879
do_group_exit+0x149/0x310 kernel/exit.c:993
get_signal+0xfb1/0x1300 kernel/signal.c:2802
arch_do_signal_or_restart+0xe7/0x11b0 arch/x86/kernel/signal.c:805
handle_signal_work kernel/entry/common.c:145 [inline]
exit_to_user_mode_loop+0xa2/0xe0 kernel/entry/common.c:169
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
The buggy address belongs to the object at ffff88811bd27800
which belongs to the cache kmalloc-512 of size 512
The buggy address is located 400 bytes inside of
512-byte region [ffff88811bd27800, ffff88811bd27a00)
The buggy address belongs to the page:
page:ffffea00046f4900 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x11bd24
head:ffffea00046f4900 order:2 compound_mapcount:0 compound_pincount:0
flags: 0x4000000000010200(slab|head)
raw: 4000000000010200 0000000000000000 0000000100000001 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 0x1d20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_HARDWALL), pid 3976, ts 149771191260, free_ts 149747830784
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_skb_with_frags+0xa3/0x560 net/core/skbuff.c:6019
sock_alloc_send_pskb+0x87f/0x9a0 net/core/sock.c:2393
sock_alloc_send_skb+0x32/0x40 net/core/sock.c:2410
__ip_append_data+0x1f8a/0x30b0 net/ipv4/ip_output.c:1111
ip_make_skb+0x1e5/0x400 net/ipv4/ip_output.c:1660
udp_sendmsg+0x1771/0x2140 net/ipv4/udp.c:1260
inet_sendmsg+0xa5/0xc0 net/ipv4/af_inet.c:830
sock_sendmsg_nosec net/socket.c:652 [inline]
__sock_sendmsg net/socket.c:664 [inline]
____sys_sendmsg+0x5be/0x8f0 net/socket.c:2377
page last free stack trace:
reset_page_owner include/linux/page_owner.h:28 [inline]
free_pages_prepare mm/page_alloc.c:1349 [inline]
__free_pages_ok+0x80b/0x830 mm/page_alloc.c:1629
free_the_page mm/page_alloc.c:5445 [inline]
__free_pages+0xd8/0x390 mm/page_alloc.c:5454
__free_slab+0xcf/0x190 mm/slub.c:1899
free_slab mm/slub.c:1914 [inline]
discard_slab mm/slub.c:1920 [inline]
unfreeze_partials+0x150/0x180 mm/slub.c:2415
put_cpu_partial+0xc1/0x180 mm/slub.c:2451
__slab_free+0x2c9/0x3a0 mm/slub.c:3100
do_slab_free mm/slub.c:3196 [inline]
___cache_free+0x10e/0x130 mm/slub.c:3215
qlink_free+0x50/0x90 mm/kasan/quarantine.c:157
qlist_free_all+0x5f/0xb0 mm/kasan/quarantine.c:176
kasan_quarantine_reduce+0x14a/0x160 mm/kasan/quarantine.c:283
__kasan_slab_alloc+0x2f/0xe0 mm/kasan/common.c:440
kasan_slab_alloc include/linux/kasan.h:244 [inline]
slab_post_alloc_hook+0x5d/0x2f0 mm/slab.h:580
slab_alloc_node mm/slub.c:2952 [inline]
slab_alloc mm/slub.c:2960 [inline]
kmem_cache_alloc+0x15a/0x2d0 mm/slub.c:2965
shmem_alloc_inode+0x1a/0x30 mm/shmem.c:3816
alloc_inode fs/inode.c:233 [inline]
new_inode_pseudo+0x62/0x210 fs/inode.c:968
new_inode+0x28/0x1e0 fs/inode.c:997
Memory state around the buggy address:
ffff88811bd27880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88811bd27900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88811bd27980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff88811bd27a00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff88811bd27a80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================
----------------
Code disassembly (best guess):
0: e8 68 25 04 00 call 0x4256d
5: 4c 89 74 24 18 mov %r14,0x18(%rsp)
a: 49 8b 06 mov (%r14),%rax
d: 48 c1 e8 3e shr $0x3e,%rax
11: 65 48 ff 04 c5 50 38 incq %gs:0x53850(,%rax,8)
18: 05 00
1a: 4c 89 a4 24 58 01 00 mov %r12,0x158(%rsp)
21: 00
22: ff b4 24 58 01 00 00 push 0x158(%rsp)
29: 9d popf
* 2a: b0 01 mov $0x1,%al <-- trapping instruction
2c: 89 84 24 94 00 00 00 mov %eax,0x94(%rsp)
33: 44 8b 3c 24 mov (%rsp),%r15d
37: e9 98 fe ff ff jmp 0xfffffed4
3c: 4c 89 f7 mov %r14,%rdi
3f: 48 rex.W