==================================================================
BUG: KASAN: use-after-free in rcu_segcblist_restempty kernel/rcu/rcu_segcblist.h:112 [inline]
BUG: KASAN: use-after-free in rcu_segcblist_accelerate+0x1e7/0x420 kernel/rcu/rcu_segcblist.c:579
Read of size 8 at addr ffff888132906190 by task syz-executor/282

CPU: 1 PID: 282 Comm: syz-executor Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
 <IRQ>
 __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_segcblist_restempty kernel/rcu/rcu_segcblist.h:112 [inline]
 rcu_segcblist_accelerate+0x1e7/0x420 kernel/rcu/rcu_segcblist.c:579
 rcu_accelerate_cbs kernel/rcu/tree.c:1150 [inline]
 rcu_report_qs_rdp kernel/rcu/tree.c:2088 [inline]
 rcu_check_quiescent_state kernel/rcu/tree.c:2141 [inline]
 rcu_core+0x7b5/0xf00 kernel/rcu/tree.c:2541
 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
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1b/0x20 arch/x86/include/asm/idtentry.h:691
RIP: 0010:kasan_check_range+0x1c4/0x2a0 mm/kasan/generic.c:-1
Code: f3 49 89 dc 49 8d 5c 24 07 4d 85 e4 49 0f 49 dc 48 83 e3 f8 49 29 dc 74 0e 41 80 3b 00 75 6b 49 ff c3 49 ff cc 75 f2 5b 41 5c <41> 5d 41 5e 41 5f 5d c3 45 84 ff 0f 85 91 00 00 00 41 f7 c7 00 ff
RSP: 0018:ffffc900011e76a8 EFLAGS: 00000256
RAX: ffffffff819fbc01 RBX: ffffea0004b903c0 RCX: ffffffff819fbc5b
RDX: 0000000000000001 RSI: 0000000000000008 RDI: ffffea0004b903c0
RBP: ffffc900011e76c0 R08: ffffea0004b903c7 R09: 1ffffd4000972078
R10: dffffc0000000000 R11: fffff94000972079 R12: 1ffffd4000972078
R13: dffffc0000000001 R14: 1ffffd4000972078 R15: dffffc0000000000
 __kasan_check_write+0x14/0x20 mm/kasan/shadow.c:37
 instrument_atomic_write include/linux/instrumented.h:87 [inline]
 set_bit include/asm-generic/bitops/instrumented-atomic.h:28 [inline]
 folio_set_referenced include/linux/page-flags.h:482 [inline]
 folio_inc_refs mm/swap.c:435 [inline]
 folio_mark_accessed+0x10b/0x4d0 mm/swap.c:473
 mark_page_accessed+0x55/0x70 mm/folio-compat.c:50
 zap_pte_range mm/memory.c:1471 [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+0x19d2/0x2360 mm/memory.c:1670
 unmap_single_vma mm/memory.c:1716 [inline]
 unmap_vmas+0x34c/0x480 mm/memory.c:1756
 exit_mmap+0x2a4/0xc10 mm/mmap.c:3371
 __mmput+0x92/0x340 kernel/fork.c:1319
 mmput+0x4b/0x150 kernel/fork.c:1343
 exit_mm kernel/exit.c:569 [inline]
 do_exit+0xa51/0x2850 kernel/exit.c:874
 do_group_exit+0x21b/0x2e0 kernel/exit.c:1030
 __do_sys_exit_group kernel/exit.c:1041 [inline]
 __se_sys_exit_group kernel/exit.c:1039 [inline]
 __x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1039
 x64_sys_call+0x7b4/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:232
 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: 0033:0x7f1bd199e019
Code: Unable to access opcode bytes at 0x7f1bd199dfef.
RSP: 002b:00007ffd4e36a9d8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 00007f1bd199e019
RDX: 00007f1bd19cb397 RSI: 0000000000000004 RDI: 0000000000000001
RBP: 00007f1bd1c267b8 R08: 0000000000000000 R09: 0000000000000003
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000008
R13: 0000000000000003 R14: 00007ffd4e36ac38 R15: 0000000000000000
 </TASK>

Allocated by task 311:
 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 43:
 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
 exit_task_work include/linux/task_work.h:39 [inline]
 do_exit+0xaf2/0x2850 kernel/exit.c:887
 __do_sys_exit kernel/exit.c:996 [inline]
 __se_sys_exit kernel/exit.c:994 [inline]
 __cfi___ia32_sys_exit+0x0/0x10 kernel/exit.c:994
 x64_sys_call+0x67/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:61
 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 ffff888132906000
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 400 bytes inside of
 512-byte region [ffff888132906000, ffff888132906200)

The buggy address belongs to the physical page:
page:ffffea0004ca4100 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x132904
head:ffffea0004ca4100 order:2 compound_mapcount:0 compound_pincount:0
flags: 0x4000000000010200(slab|head|zone=1)
raw: 4000000000010200 0000000000000000 dead000000000122 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 0x152a20(GFP_ATOMIC|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_HARDWALL), pid 19, tgid 19 (kworker/0:1), ts 25764858029, free_ts 25745249821
 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+0xa4/0x1e0 mm/slab_common.c:951
 kmalloc include/linux/slab.h:568 [inline]
 kzalloc include/linux/slab.h:699 [inline]
 neigh_alloc net/core/neighbour.c:494 [inline]
 ___neigh_create+0x6e3/0x1db0 net/core/neighbour.c:648
 __neigh_create+0x31/0x40 net/core/neighbour.c:737
 ip6_finish_output2+0xaaf/0x18b0 net/ipv6/ip6_output.c:129
 __ip6_finish_output net/ipv6/ip6_output.c:205 [inline]
 ip6_finish_output+0x60b/0xbe0 net/ipv6/ip6_output.c:216
 NF_HOOK_COND include/linux/netfilter.h:294 [inline]
 ip6_output+0x1fa/0x410 net/ipv6/ip6_output.c:237
 dst_output include/net/dst.h:453 [inline]
 NF_HOOK include/linux/netfilter.h:305 [inline]
 mld_sendpack+0x7ce/0xda0 net/ipv6/mcast.c:1825
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_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
 kvfree+0x35/0x40 mm/util.c:639
 xt_free_table_info+0x6d/0x180 net/netfilter/x_tables.c:1231
 __do_replace+0x7bd/0x960 net/ipv6/netfilter/ip6_tables.c:1103
 do_replace net/ipv6/netfilter/ip6_tables.c:1160 [inline]
 do_ip6t_set_ctl+0xb2c/0xe00 net/ipv6/netfilter/ip6_tables.c:1646

Memory state around the buggy address:
 ffff888132906080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888132906100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888132906180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                         ^
 ffff888132906200: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888132906280: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================
----------------
Code disassembly (best guess):
   0:	f3 49 89 dc          	repz mov %rbx,%r12
   4:	49 8d 5c 24 07       	lea    0x7(%r12),%rbx
   9:	4d 85 e4             	test   %r12,%r12
   c:	49 0f 49 dc          	cmovns %r12,%rbx
  10:	48 83 e3 f8          	and    $0xfffffffffffffff8,%rbx
  14:	49 29 dc             	sub    %rbx,%r12
  17:	74 0e                	je     0x27
  19:	41 80 3b 00          	cmpb   $0x0,(%r11)
  1d:	75 6b                	jne    0x8a
  1f:	49 ff c3             	inc    %r11
  22:	49 ff cc             	dec    %r12
  25:	75 f2                	jne    0x19
  27:	5b                   	pop    %rbx
  28:	41 5c                	pop    %r12
* 2a:	41 5d                	pop    %r13 <-- trapping instruction
  2c:	41 5e                	pop    %r14
  2e:	41 5f                	pop    %r15
  30:	5d                   	pop    %rbp
  31:	c3                   	ret
  32:	45 84 ff             	test   %r15b,%r15b
  35:	0f 85 91 00 00 00    	jne    0xcc
  3b:	41                   	rex.B
  3c:	f7                   	.byte 0xf7
  3d:	c7                   	.byte 0xc7
  3e:	00 ff                	add    %bh,%bh