==================================================================
BUG: KASAN: out-of-bounds in hlist_add_head include/linux/list.h:787 [inline]
BUG: KASAN: out-of-bounds in enqueue_timer kernel/time/timer.c:541 [inline]
BUG: KASAN: out-of-bounds in __internal_add_timer+0x2a6/0x4a0 kernel/time/timer.c:554
Write of size 8 at addr ffff8881e6f331c8 by task syz-executor.0/1795

CPU: 0 PID: 1795 Comm: syz-executor.0 Not tainted 5.4.125-syzkaller-00245-ga57aec00e1ca #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1d8/0x24e lib/dump_stack.c:118
 print_address_description+0x9b/0x650 mm/kasan/report.c:384
 __kasan_report+0x182/0x260 mm/kasan/report.c:516
 kasan_report+0x30/0x60 mm/kasan/common.c:653
 hlist_add_head include/linux/list.h:787 [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+0xab9/0x1c70 kernel/time/timer.c:1065
 tun_flow_init drivers/net/tun.c:1376 [inline]
 tun_set_iff drivers/net/tun.c:2848 [inline]
 __tun_chr_ioctl+0x3408/0x4d20 drivers/net/tun.c:3143
 do_vfs_ioctl+0x76a/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+0xcb/0x1e0 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x4665d9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 bc ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007faf7d790188 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 000000000056bf80 RCX: 00000000004665d9
RDX: 00000000200000c0 RSI: 00000000400454ca RDI: 0000000000000004
RBP: 00000000004bfcb9 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056bf80
R13: 00007ffd6230ee9f R14: 00007faf7d790300 R15: 0000000000022000

The buggy address belongs to the page:
page:ffffea00079bccc0 refcount:0 mapcount:0 mapping:0000000000000000 index:0x0
flags: 0x8000000000000000()
raw: 8000000000000000 ffffea00079bcc88 ffffea0007985b48 0000000000000000
raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as freed
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x400dc0(GFP_KERNEL_ACCOUNT|__GFP_ZERO)
 set_page_owner include/linux/page_owner.h:31 [inline]
 post_alloc_hook mm/page_alloc.c:2165 [inline]
 prep_new_page+0x19a/0x380 mm/page_alloc.c:2171
 get_page_from_freelist+0x550/0x8b0 mm/page_alloc.c:3794
 __alloc_pages_nodemask+0x3a2/0x880 mm/page_alloc.c:4855
 __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]
 __pte_alloc_one include/asm-generic/pgalloc.h:63 [inline]
 pte_alloc_one+0x1b/0xb0 arch/x86/mm/pgtable.c:26
 __do_fault mm/memory.c:3190 [inline]
 do_shared_fault mm/memory.c:3651 [inline]
 do_fault mm/memory.c:3729 [inline]
 handle_pte_fault mm/memory.c:3956 [inline]
 __handle_mm_fault mm/memory.c:4080 [inline]
 handle_mm_fault+0x1f56/0x42f0 mm/memory.c:4117
 do_user_addr_fault+0x4a0/0xb40 arch/x86/mm/fault.c:1469
 page_fault+0x2f/0x40 arch/x86/entry/entry_64.S:1203
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_pcp_prepare+0x1a9/0x270 mm/page_alloc.c:1233
 free_unref_page_prepare mm/page_alloc.c:3085 [inline]
 free_unref_page_list+0x115/0x6c0 mm/page_alloc.c:3154
 release_pages+0x98f/0x9d0 mm/swap.c:842
 tlb_batch_pages_flush mm/mmu_gather.c:49 [inline]
 tlb_flush_mmu_free mm/mmu_gather.c:184 [inline]
 tlb_flush_mmu+0x77f/0x910 mm/mmu_gather.c:191
 tlb_finish_mmu+0xcb/0x200 mm/mmu_gather.c:272
 exit_mmap+0x2e8/0x540 mm/mmap.c:3176
 __mmput+0x34/0x240 kernel/fork.c:1089
 exit_mm kernel/exit.c:489 [inline]
 do_exit+0xc19/0x2bf0 kernel/exit.c:799
 do_group_exit+0x15c/0x2c0 kernel/exit.c:910
 get_signal+0x164f/0x1fc0 kernel/signal.c:2745
 do_signal+0x8d/0x610 arch/x86/kernel/signal.c:793
 exit_to_usermode_loop arch/x86/entry/common.c:159 [inline]
 prepare_exit_to_usermode+0x207/0x310 arch/x86/entry/common.c:194
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Memory state around the buggy address:
 ffff8881e6f33080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8881e6f33100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff8881e6f33180: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                              ^
 ffff8881e6f33200: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8881e6f33280: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================
device syzkaller1 entered promiscuous mode
device syzkaller1 left promiscuous mode