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BUG: KASAN: slab-out-of-bounds in __write_once_size include/linux/compiler.h:295 [inline]
BUG: KASAN: slab-out-of-bounds in __hlist_del include/linux/list.h:789 [inline]
BUG: KASAN: slab-out-of-bounds in detach_timer kernel/time/timer.c:824 [inline]
BUG: KASAN: slab-out-of-bounds in detach_if_pending+0x160/0x360 kernel/time/timer.c:841
Write of size 8 at addr ffff8881e65bb1c0 by task syz-executor.4/6509

CPU: 1 PID: 6509 Comm: syz-executor.4 Tainted: G        W         5.4.274-syzkaller-00002-g6f97bd951d82 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/02/2024
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1d8/0x241 lib/dump_stack.c:118
 print_address_description+0x8c/0x600 mm/kasan/report.c:384
 __kasan_report+0xf3/0x120 mm/kasan/report.c:516
 kasan_report+0x30/0x60 mm/kasan/common.c:653
 __write_once_size include/linux/compiler.h:295 [inline]
 __hlist_del include/linux/list.h:789 [inline]
 detach_timer kernel/time/timer.c:824 [inline]
 detach_if_pending+0x160/0x360 kernel/time/timer.c:841
 try_to_del_timer_sync kernel/time/timer.c:1267 [inline]
 del_timer_sync+0x13c/0x230 kernel/time/timer.c:1410
 tun_flow_uninit+0x2c/0x280 drivers/net/tun.c:1452
 tun_free_netdev+0x77/0x190 drivers/net/tun.c:2402
 netdev_run_todo+0xb7f/0xdf0 net/core/dev.c:9458
 tun_detach drivers/net/tun.c:766 [inline]
 tun_chr_close+0xc1/0x130 drivers/net/tun.c:3558
 __fput+0x262/0x680 fs/file_table.c:281
 task_work_run+0x140/0x170 kernel/task_work.c:113
 exit_task_work include/linux/task_work.h:22 [inline]
 do_exit+0xcaf/0x2bc0 kernel/exit.c:859
 do_group_exit+0x138/0x300 kernel/exit.c:982
 __do_sys_exit_group kernel/exit.c:993 [inline]
 __se_sys_exit_group kernel/exit.c:991 [inline]
 __x64_sys_exit_group+0x3b/0x40 kernel/exit.c:991
 do_syscall_64+0xca/0x1c0 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x5c/0xc1
RIP: 0033:0x7f1900a80ea9
Code: Bad RIP value.
RSP: 002b:00007ffdc3434628 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f1900a80ea9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000043
RBP: 00007f1900aceaf8 R08: 00007ffdc34323c7 R09: 00007f1900bb7f40
R10: 0000000000000009 R11: 0000000000000246 R12: 0000000000000001
R13: 00007f1900bb7f40 R14: 00007ffdc3434800 R15: 00000000ffffffff

Allocated by task 1476:
 save_stack mm/kasan/common.c:70 [inline]
 set_track mm/kasan/common.c:78 [inline]
 __kasan_kmalloc+0x171/0x210 mm/kasan/common.c:529
 kmalloc include/linux/slab.h:561 [inline]
 kzalloc include/linux/slab.h:690 [inline]
 neigh_alloc net/core/neighbour.c:439 [inline]
 ___neigh_create+0x6d2/0x1ae0 net/core/neighbour.c:592
 ip6_finish_output2+0x965/0x18e0 net/ipv6/ip6_output.c:141
 NF_HOOK_COND include/linux/netfilter.h:292 [inline]
 ip6_output+0x1b3/0x430 net/ipv6/ip6_output.c:248
 dst_output include/net/dst.h:438 [inline]
 NF_HOOK include/linux/netfilter.h:303 [inline]
 ndisc_send_skb+0x702/0xc30 net/ipv6/ndisc.c:509
 ndisc_send_ns+0x64d/0x830 net/ipv6/ndisc.c:651
 addrconf_dad_work+0xb91/0x16f0 net/ipv6/addrconf.c:4194
 process_one_work+0x765/0xd20 kernel/workqueue.c:2290
 worker_thread+0xaef/0x1470 kernel/workqueue.c:2436
 kthread+0x2da/0x360 kernel/kthread.c:288
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:354

Freed by task 0:
(stack is not available)

The buggy address belongs to the object at ffff8881e65bb000
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 448 bytes inside of
 512-byte region [ffff8881e65bb000, ffff8881e65bb200)
The buggy address belongs to the page:
page:ffffea0007996e00 refcount:1 mapcount:0 mapping:ffff8881f5c02500 index:0x0 compound_mapcount: 0
flags: 0x8000000000010200(slab|head)
raw: 8000000000010200 dead000000000100 dead000000000122 ffff8881f5c02500
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 0x1d2a20(GFP_ATOMIC|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_HARDWALL)
 set_page_owner include/linux/page_owner.h:31 [inline]
 post_alloc_hook mm/page_alloc.c:2165 [inline]
 prep_new_page+0x18f/0x370 mm/page_alloc.c:2171
 get_page_from_freelist+0x2d13/0x2d90 mm/page_alloc.c:3794
 __alloc_pages_nodemask+0x393/0x840 mm/page_alloc.c:4893
 alloc_slab_page+0x39/0x3c0 mm/slub.c:343
 allocate_slab mm/slub.c:1683 [inline]
 new_slab+0x97/0x440 mm/slub.c:1749
 new_slab_objects mm/slub.c:2505 [inline]
 ___slab_alloc+0x2fe/0x490 mm/slub.c:2667
 __slab_alloc+0x62/0xa0 mm/slub.c:2707
 slab_alloc_node mm/slub.c:2792 [inline]
 slab_alloc mm/slub.c:2837 [inline]
 __kmalloc_track_caller+0x16d/0x2b0 mm/slub.c:4449
 __kmalloc_reserve net/core/skbuff.c:142 [inline]
 __alloc_skb+0xb4/0x4d0 net/core/skbuff.c:210
 alloc_skb include/linux/skbuff.h:1080 [inline]
 ndisc_alloc_skb+0xee/0x2c0 net/ipv6/ndisc.c:421
 ndisc_send_ns+0x29d/0x830 net/ipv6/ndisc.c:627
 addrconf_dad_work+0xb91/0x16f0 net/ipv6/addrconf.c:4194
 process_one_work+0x765/0xd20 kernel/workqueue.c:2290
 worker_thread+0xaef/0x1470 kernel/workqueue.c:2436
 kthread+0x2da/0x360 kernel/kthread.c:288
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:354
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1176 [inline]
 __free_pages_ok+0x847/0x950 mm/page_alloc.c:1438
 free_the_page mm/page_alloc.c:4955 [inline]
 __free_pages+0x91/0x140 mm/page_alloc.c:4961
 device_release+0x6b/0x190 drivers/base/core.c:1776
 kobject_cleanup lib/kobject.c:716 [inline]
 kobject_release lib/kobject.c:747 [inline]
 kref_put include/linux/kref.h:65 [inline]
 kobject_put+0x1e6/0x2f0 lib/kobject.c:764
 tun_set_iff+0x870/0xdc0 drivers/net/tun.c:2919
 __tun_chr_ioctl+0x8a9/0x1d00 drivers/net/tun.c:3182
 do_vfs_ioctl+0x742/0x1720 fs/ioctl.c:47
 ksys_ioctl fs/ioctl.c:742 [inline]
 __do_sys_ioctl fs/ioctl.c:749 [inline]
 __se_sys_ioctl fs/ioctl.c:747 [inline]
 __x64_sys_ioctl+0xd4/0x110 fs/ioctl.c:747
 do_syscall_64+0xca/0x1c0 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x5c/0xc1

Memory state around the buggy address:
 ffff8881e65bb080: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8881e65bb100: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff8881e65bb180: 00 fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                                           ^
 ffff8881e65bb200: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8881e65bb280: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
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