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BUG: KASAN: slab-out-of-bounds in hlist_add_head include/linux/list.h:796 [inline]
BUG: KASAN: slab-out-of-bounds in enqueue_timer kernel/time/timer.c:541 [inline]
BUG: KASAN: slab-out-of-bounds in __internal_add_timer+0x2a6/0x4a0 kernel/time/timer.c:554
Write of size 8 at addr ffff8881e93af1c8 by task syz-executor.1/2377

CPU: 0 PID: 2377 Comm: syz-executor.1 Not tainted 5.4.219-syzkaller-00093-g1c84384fbdc7 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1d8/0x241 lib/dump_stack.c:118
 print_address_description+0x8c/0x630 mm/kasan/report.c:384
 __kasan_report+0xf6/0x130 mm/kasan/report.c:516
 kasan_report+0x30/0x60 mm/kasan/common.c:653
 hlist_add_head include/linux/list.h:796 [inline]
 enqueue_timer kernel/time/timer.c:541 [inline]
 __internal_add_timer+0x2a6/0x4a0 kernel/time/timer.c:554
 internal_add_timer kernel/time/timer.c:604 [inline]
 __mod_timer+0xaad/0x1c90 kernel/time/timer.c:1065
 tun_set_iff+0x8ca/0x1050 drivers/net/tun.c:2865
 __tun_chr_ioctl+0x88e/0x1ee0 drivers/net/tun.c:3160
 do_vfs_ioctl+0x744/0x1730 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+0xcb/0x1c0 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x5c/0xc1

The buggy address belongs to the page:
page:ffffea0007a4eb00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 compound_mapcount: 0
flags: 0x8000000000010000(head)
raw: 8000000000010000 dead000000000100 dead000000000122 0000000000000000
raw: 0000000000000000 0000000000000000 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 0x140dc0(GFP_USER|__GFP_COMP|__GFP_ZERO)
 set_page_owner include/linux/page_owner.h:31 [inline]
 post_alloc_hook mm/page_alloc.c:2165 [inline]
 prep_new_page+0x194/0x380 mm/page_alloc.c:2171
 get_page_from_freelist+0x524/0x560 mm/page_alloc.c:3794
 __alloc_pages_nodemask+0x372/0x860 mm/page_alloc.c:4891
 __alloc_pages include/linux/gfp.h:503 [inline]
 __alloc_pages_node include/linux/gfp.h:516 [inline]
 alloc_pages_node include/linux/gfp.h:530 [inline]
 kmalloc_order mm/slab_common.c:1342 [inline]
 kmalloc_order_trace+0x2a/0xf0 mm/slab_common.c:1358
 kmalloc_large include/linux/slab.h:485 [inline]
 kmalloc include/linux/slab.h:549 [inline]
 kzalloc include/linux/slab.h:690 [inline]
 tipc_nametbl_init+0x93/0x260 net/tipc/name_table.c:738
 tipc_init_net+0x229/0x360 net/tipc/core.c:74
 ops_init+0x278/0x350 net/core/net_namespace.c:137
 setup_net+0x21b/0xa70 net/core/net_namespace.c:338
 copy_net_ns+0x31a/0x510 net/core/net_namespace.c:479
 create_new_namespaces+0x4e3/0x5f0 kernel/nsproxy.c:103
 copy_namespaces+0x169/0x1b0 kernel/nsproxy.c:161
 copy_process+0x12cd/0x3230 kernel/fork.c:2044
 _do_fork+0x196/0x8d0 kernel/fork.c:2391
 __do_sys_clone kernel/fork.c:2549 [inline]
 __se_sys_clone kernel/fork.c:2530 [inline]
 __x64_sys_clone+0x287/0x2f0 kernel/fork.c:2530
 do_syscall_64+0xcb/0x1c0 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x5c/0xc1
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+0x7fe/0x930 mm/page_alloc.c:1438
 free_the_page mm/page_alloc.c:4953 [inline]
 __free_pages+0x8f/0x250 mm/page_alloc.c:4959
 kfree+0x1ef/0x260 mm/slub.c:4068
 device_release+0x70/0x1a0 drivers/base/core.c:1776
 kobject_cleanup lib/kobject.c:708 [inline]
 kobject_release+0x20c/0x330 lib/kobject.c:739
 netdev_run_todo+0xc1b/0xdb0 net/core/dev.c:9457
 tun_detach drivers/net/tun.c:760 [inline]
 tun_chr_close+0xc0/0xd0 drivers/net/tun.c:3534
 __fput+0x261/0x680 fs/file_table.c:281
 task_work_run+0x186/0x1b0 kernel/task_work.c:113
 tracehook_notify_resume include/linux/tracehook.h:188 [inline]
 exit_to_usermode_loop+0x1ba/0x1d0 arch/x86/entry/common.c:163
 prepare_exit_to_usermode+0x17c/0x1d0 arch/x86/entry/common.c:194
 entry_SYSCALL_64_after_hwframe+0x5c/0xc1

Memory state around the buggy address:
 ffff8881e93af080: fe fe fe fe fe fe fe fe fe fe fe fe fe fe fe fe
 ffff8881e93af100: fe fe fe fe fe fe fe fe fe fe fe fe fe fe fe fe
>ffff8881e93af180: fe fe fe fe fe fe fe fe fe fe fe fe fe fe fe fe
                                              ^
 ffff8881e93af200: fe fe fe fe fe fe fe fe fe fe fe fe fe fe fe fe
 ffff8881e93af280: fe fe fe fe fe fe fe fe fe fe fe fe fe fe fe fe
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