==================================================================
BUG: KASAN: use-after-free in hlist_add_head include/linux/list.h:796 [inline]
BUG: KASAN: use-after-free in enqueue_timer kernel/time/timer.c:541 [inline]
BUG: KASAN: use-after-free in __internal_add_timer+0x2a6/0x4a0 kernel/time/timer.c:554
Write of size 8 at addr ffff8881db87f1c8 by task syz-executor.4/29157

CPU: 0 PID: 29157 Comm: syz-executor.4 Not tainted 5.4.197-syzkaller-00005-g704c7d053806 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/26/2022
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
 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+0x9ce/0x1a40 kernel/time/timer.c:1065
 tun_set_iff+0x8ca/0x1050 drivers/net/tun.c:2854
 __tun_chr_ioctl+0x6c7/0x1b70 drivers/net/tun.c:3149
 do_vfs_ioctl+0x6d1/0x15b0 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+0x44/0xa9
RIP: 0033:0x7ff0b8fb13c9
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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ff0b8127168 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007ff0b90c3f80 RCX: 00007ff0b8fb13c9
RDX: 00000000200004c0 RSI: 00000000400454ca RDI: 0000000000000005
RBP: 00007ff0b900c33f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffe5052c44f R14: 00007ff0b8127300 R15: 0000000000022000

The buggy address belongs to the page:
page:ffffea00076e1fc0 refcount:0 mapcount:0 mapping:0000000000000000 index:0x0
flags: 0x8000000000000000()
raw: 8000000000000000 0000000000000000 ffffea0007057f88 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 2, migratetype Unmovable, gfp_mask 0x152dc0(GFP_USER|__GFP_NOWARN|__GFP_NORETRY|__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_node include/linux/slab.h:422 [inline]
 kmalloc_node include/linux/slab.h:599 [inline]
 bpf_map_area_alloc+0x47/0x90 kernel/bpf/syscall.c:149
 prealloc_init kernel/bpf/hashtab.c:142 [inline]
 htab_map_alloc+0x79a/0x11f0 kernel/bpf/hashtab.c:378
 find_and_alloc_map kernel/bpf/syscall.c:122 [inline]
 map_create kernel/bpf/syscall.c:573 [inline]
 __do_sys_bpf kernel/bpf/syscall.c:2871 [inline]
 __se_sys_bpf+0x2fe1/0xb990 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
 kfree+0x1ef/0x260 mm/slub.c:4068
 htab_free_elems kernel/bpf/hashtab.c:116 [inline]
 prealloc_destroy kernel/bpf/hashtab.c:194 [inline]
 htab_map_free+0x5a2/0x6f0 kernel/bpf/hashtab.c:1231
 bpf_map_free_deferred+0xa6/0x100 kernel/bpf/syscall.c:311
 process_one_work+0x6ca/0xc40 kernel/workqueue.c:2287
 worker_thread+0xae0/0x1440 kernel/workqueue.c:2433
 kthread+0x2d8/0x360 kernel/kthread.c:288
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:352

Memory state around the buggy address:
 ffff8881db87f080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8881db87f100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff8881db87f180: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                              ^
 ffff8881db87f200: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8881db87f280: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================