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BUG: KASAN: use-after-free in __write_once_size include/linux/compiler.h:295 [inline]
BUG: KASAN: use-after-free in __hlist_del include/linux/list.h:771 [inline]
BUG: KASAN: use-after-free in detach_timer kernel/time/timer.c:824 [inline]
BUG: KASAN: use-after-free in detach_if_pending kernel/time/timer.c:841 [inline]
BUG: KASAN: use-after-free in try_to_del_timer_sync+0x27c/0x460 kernel/time/timer.c:1238
Write of size 8 at addr ffff8881d907b1c0 by task syz-executor.3/13749

CPU: 1 PID: 13749 Comm: syz-executor.3 Not tainted 5.4.210-syzkaller-00006-gc80a5b2e7f63 #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
 __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:1398 [inline]
 tun_free_netdev+0x99/0x3b0 drivers/net/tun.c:2339
 netdev_run_todo+0xb41/0xdb0 net/core/dev.c:9445
 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
 exit_task_work include/linux/task_work.h:22 [inline]
 do_exit+0xce6/0x2d30 kernel/exit.c:812
 do_group_exit+0x136/0x300 kernel/exit.c:910
 get_signal+0xd99/0x13f0 kernel/signal.c:2735
 do_signal+0xb0/0x1200 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
 ret_from_fork+0x15/0x30 arch/x86/entry/entry_64.S:344
RIP: 0033:0x7fd5ba0fe501
Code: Bad RIP value.
RSP: 002b:00007fd5b8d682f0 EFLAGS: 00000206 ORIG_RAX: 0000000000000038
RAX: 0000000000000000 RBX: 00007fd5b8d68700 RCX: 00007fd5ba0fe501
RDX: 00007fd5b8d689d0 RSI: 00007fd5b8d682f0 RDI: 00000000003d0f00
RBP: 00007fffa00ab310 R08: 00007fd5b8d68700 R09: 00007fd5b8d68700
R10: 00007fd5b8d689d0 R11: 0000000000000206 R12: 00007fffa00ab17e
R13: 00007fffa00ab17f R14: 00007fd5b8d68300 R15: 0000000000022000

The buggy address belongs to the page:
page:ffffea0007641ec0 refcount:0 mapcount:0 mapping:0000000000000000 index:0x0
flags: 0x8000000000000000()
raw: 8000000000000000 0000000000000000 ffffea0007641e88 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 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: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+0x100/0xb740 kernel/bpf/verifier.c:9534
 bpf_prog_load kernel/bpf/syscall.c:1724 [inline]
 __do_sys_bpf kernel/bpf/syscall.c:2889 [inline]
 __se_sys_bpf+0x77ec/0xbba0 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+0x7fe/0x930 mm/page_alloc.c:1438
 free_the_page mm/page_alloc.c:4919 [inline]
 __free_pages+0x8f/0x250 mm/page_alloc.c:4925
 kfree+0x1ef/0x260 mm/slub.c:4068
 bpf_check+0x4b27/0xb740 kernel/bpf/verifier.c:9704
 bpf_prog_load kernel/bpf/syscall.c:1724 [inline]
 __do_sys_bpf kernel/bpf/syscall.c:2889 [inline]
 __se_sys_bpf+0x77ec/0xbba0 kernel/bpf/syscall.c:2847
 do_syscall_64+0xcb/0x1c0 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Memory state around the buggy address:
 ffff8881d907b080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8881d907b100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff8881d907b180: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                           ^
 ffff8881d907b200: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8881d907b280: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
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