==================================================================
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:771 [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 kernel/time/timer.c:841 [inline]
BUG: KASAN: slab-out-of-bounds in try_to_del_timer_sync+0x27c/0x460 kernel/time/timer.c:1238
Write of size 8 at addr ffff8881dc7031c0 by task syz-executor.4/3115

CPU: 1 PID: 3115 Comm: syz-executor.4 Not tainted 5.4.197-syzkaller-00007-g19a66b6f3cd8 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/22/2022
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x18e/0x1d5 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
 __write_once_size include/linux/compiler.h:295 [inline]
 __hlist_del include/linux/list.h:771 [inline]
 detach_timer kernel/time/timer.c:824 [inline]
 detach_if_pending kernel/time/timer.c:841 [inline]
 try_to_del_timer_sync+0x27c/0x460 kernel/time/timer.c:1238
 del_timer_sync+0x74/0xd0 kernel/time/timer.c:1379
 tun_flow_uninit drivers/net/tun.c:1387 [inline]
 tun_free_netdev+0x99/0x3b0 drivers/net/tun.c:2328
 netdev_run_todo+0xa3c/0xc80 net/core/dev.c:9445
 tun_detach drivers/net/tun.c:751 [inline]
 tun_chr_close+0xc0/0xd0 drivers/net/tun.c:3523
 __fput+0x261/0x680 fs/file_table.c:281
 task_work_run+0x186/0x1b0 kernel/task_work.c:113
 exit_task_work include/linux/task_work.h:22 [inline]
 do_exit+0xbe1/0x2b40 kernel/exit.c:812
 do_group_exit+0x136/0x300 kernel/exit.c:910
 get_signal+0xd99/0x13f0 kernel/signal.c:2735
 do_signal+0x3b/0x540 arch/x86/kernel/signal.c:809
 exit_to_usermode_loop+0xdd/0x1d0 arch/x86/entry/common.c:159
 prepare_exit_to_usermode+0x17c/0x1d0 arch/x86/entry/common.c:194
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x7f8ee7d98279
Code: Bad RIP value.
RSP: 002b:00007f8ee6eab168 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffea RBX: 00007f8ee7eab1f0 RCX: 00007f8ee7d98279
RDX: 0000000000000010 RSI: 00000000400454d0 RDI: 0000000000000003
RBP: 00007f8ee7df2189 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffc7f230e0f R14: 00007f8ee6eab300 R15: 0000000000022000

The buggy address belongs to the page:
page:ffffea000771c000 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+0x2ab/0x6f0 mm/page_alloc.c:4857
 __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]
 bpf_check+0x58/0xb220 kernel/bpf/verifier.c:9533
 bpf_prog_load kernel/bpf/syscall.c:1724 [inline]
 __do_sys_bpf kernel/bpf/syscall.c:2889 [inline]
 __se_sys_bpf+0x7620/0xb990 kernel/bpf/syscall.c:2847
 do_syscall_64+0xcb/0x1c0 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
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+0x7ee/0x920 mm/page_alloc.c:1438
 free_the_page mm/page_alloc.c:4919 [inline]
 __free_pages+0x45/0x1e0 mm/page_alloc.c:4925
 stack_depot_save+0x37e/0x470 lib/stackdepot.c:300
 save_stack mm/kasan/common.c:72 [inline]
 set_track mm/kasan/common.c:78 [inline]
 kasan_set_free_info mm/kasan/common.c:345 [inline]
 __kasan_slab_free+0x1e3/0x240 mm/kasan/common.c:487
 slab_free_hook mm/slub.c:1455 [inline]
 slab_free_freelist_hook+0x80/0x150 mm/slub.c:1494
 slab_free mm/slub.c:3080 [inline]
 kmem_cache_free+0xa9/0x1d0 mm/slub.c:3096
 netlink_broadcast_filtered+0x1005/0x1110 net/netlink/af_netlink.c:1522
 netlink_broadcast+0x35/0x50 net/netlink/af_netlink.c:1544
 uevent_net_broadcast_tagged lib/kobject_uevent.c:372 [inline]
 kobject_uevent_net_broadcast+0x4b0/0x550 lib/kobject_uevent.c:412
 kobject_uevent_env+0x552/0x700 lib/kobject_uevent.c:593
 device_del+0xe4a/0xf40 drivers/base/core.c:3095
 rollback_registered_many+0xd9f/0x11c0 net/core/dev.c:8640
 rollback_registered net/core/dev.c:8658 [inline]
 unregister_netdevice_queue+0x2bb/0x470 net/core/dev.c:9754
 unregister_netdevice include/linux/netdevice.h:2725 [inline]
 __tun_detach+0xedd/0x1980 drivers/net/tun.c:731
 tun_detach drivers/net/tun.c:748 [inline]
 tun_chr_close+0x8e/0xd0 drivers/net/tun.c:3523
 __fput+0x261/0x680 fs/file_table.c:281

Memory state around the buggy address:
 ffff8881dc703080: fe fe fe fe fe fe fe fe fe fe fe fe fe fe fe fe
 ffff8881dc703100: fe fe fe fe fe fe fe fe fe fe fe fe fe fe fe fe
>ffff8881dc703180: fe fe fe fe fe fe fe fe fe fe fe fe fe fe fe fe
                                           ^
 ffff8881dc703200: fe fe fe fe fe fe fe fe fe fe fe fe fe fe fe fe
 ffff8881dc703280: fe fe fe fe fe fe fe fe fe fe fe fe fe fe fe fe
==================================================================