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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 ffff8881b9e271c0 by task syz-executor.1/5557

CPU: 0 PID: 5557 Comm: syz-executor.1 Not tainted 5.4.210-syzkaller-00005-ge9f865cb240f #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
 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+0x44/0xa9
RIP: 0033:0x7fce9775640b
Code: 0f 05 48 3d 00 f0 ff ff 77 45 c3 0f 1f 40 00 48 83 ec 18 89 7c 24 0c e8 63 fc ff ff 8b 7c 24 0c 41 89 c0 b8 03 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 35 44 89 c7 89 44 24 0c e8 a1 fc ff ff 8b 44
RSP: 002b:00007ffef9461690 EFLAGS: 00000293 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 0000000000000005 RCX: 00007fce9775640b
RDX: 0000000000000000 RSI: 0000001b2ee20fe8 RDI: 0000000000000004
RBP: 00007fce978c6980 R08: 0000000000000000 R09: 000000003e6f72a4
R10: 0000000000000000 R11: 0000000000000293 R12: 000000000025b9d3
R13: 00007ffef9461790 R14: 00007fce978c5050 R15: 0000000000000226

The buggy address belongs to the page:
page:ffffea0006e789c0 refcount:0 mapcount:0 mapping:0000000000000000 index:0x0
flags: 0x8000000000000000()
raw: 8000000000000000 0000000000000000 dead000000000122 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 0x146dc0(GFP_USER|__GFP_NOWARN|__GFP_RETRY_MAYFAIL|__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_node include/linux/slab.h:422 [inline]
 kmalloc_node include/linux/slab.h:599 [inline]
 kvmalloc_node+0x7e/0xf0 mm/util.c:596
 kvmalloc include/linux/mm.h:759 [inline]
 kvzalloc include/linux/mm.h:767 [inline]
 alloc_netdev_mqs+0x86/0xc30 net/core/dev.c:9597
 tun_set_iff+0x4f9/0x1050 drivers/net/tun.c:2825
 __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+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
 netdev_freemem net/core/dev.c:9551 [inline]
 alloc_netdev_mqs+0x192/0xc30 net/core/dev.c:9669
 tun_set_iff+0x4f9/0x1050 drivers/net/tun.c:2825
 __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+0x44/0xa9

Memory state around the buggy address:
 ffff8881b9e27080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8881b9e27100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff8881b9e27180: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                           ^
 ffff8881b9e27200: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8881b9e27280: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
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