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BUG: KASAN: use-after-free in __hlist_del include/linux/list.h:764 [inline]
BUG: KASAN: use-after-free in detach_timer kernel/time/timer.c:815 [inline]
BUG: KASAN: use-after-free in detach_if_pending kernel/time/timer.c:832 [inline]
BUG: KASAN: use-after-free in try_to_del_timer_sync+0x3ee/0x480 kernel/time/timer.c:1226
Write of size 8 at addr ffff88813a0b3188 by task syz-executor.3/2498

CPU: 1 PID: 2498 Comm: syz-executor.3 Not tainted 5.4.51-syzkaller-00138-g22b73c7316d2 #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+0x14a/0x1ce lib/dump_stack.c:118
 print_address_description+0x93/0x620 mm/kasan/report.c:374
 __kasan_report+0x16d/0x1e0 mm/kasan/report.c:506
 kasan_report+0x36/0x60 mm/kasan/common.c:634
 __hlist_del include/linux/list.h:764 [inline]
 detach_timer kernel/time/timer.c:815 [inline]
 detach_if_pending kernel/time/timer.c:832 [inline]
 try_to_del_timer_sync+0x3ee/0x480 kernel/time/timer.c:1226
 del_timer_sync+0x74/0xe0 kernel/time/timer.c:1365
 tun_flow_uninit drivers/net/tun.c:1374 [inline]
 tun_free_netdev+0x99/0x3a0 drivers/net/tun.c:2307
 netdev_run_todo+0xbe3/0xe90 net/core/dev.c:9351
 tun_detach drivers/net/tun.c:743 [inline]
 tun_chr_close+0xc0/0xd0 drivers/net/tun.c:3461
 __fput+0x27d/0x6c0 fs/file_table.c:280
 task_work_run+0x176/0x1a0 kernel/task_work.c:113
 tracehook_notify_resume include/linux/tracehook.h:188 [inline]
 exit_to_usermode_loop arch/x86/entry/common.c:163 [inline]
 prepare_exit_to_usermode+0x286/0x2e0 arch/x86/entry/common.c:194
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x416721
Code: 75 14 b8 03 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 04 1b 00 00 c3 48 83 ec 08 e8 0a fc ff ff 48 89 04 24 b8 03 00 00 00 0f 05 <48> 8b 3c 24 48 89 c2 e8 53 fc ff ff 48 89 d0 48 83 c4 08 48 3d 01
RSP: 002b:00007ffc20ead8a0 EFLAGS: 00000293 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 0000000000000004 RCX: 0000000000416721
RDX: 0000001b31a20000 RSI: 000000000000162b RDI: 0000000000000003
RBP: 0000000000000001 R08: 00000000f2b5962f R09: 0000000000000000
R10: 00007ffc20ead990 R11: 0000000000000293 R12: 00000000007908e0
R13: 0000000000262cd2 R14: ffffffffffffffff R15: 000000000078bf0c

Allocated by task 2492:
 save_stack mm/kasan/common.c:69 [inline]
 set_track mm/kasan/common.c:77 [inline]
 __kasan_kmalloc+0x12c/0x1c0 mm/kasan/common.c:510
 slab_post_alloc_hook mm/slab.h:584 [inline]
 slab_alloc_node mm/slub.c:2793 [inline]
 slab_alloc mm/slub.c:2801 [inline]
 kmem_cache_alloc+0x1d5/0x260 mm/slub.c:2806
 kmem_cache_zalloc include/linux/slab.h:680 [inline]
 alloc_vfsmnt+0x24/0x470 fs/namespace.c:177
 clone_mnt+0x68/0xca0 fs/namespace.c:1037
 copy_tree+0x485/0xc00 fs/namespace.c:1817
 propagate_one+0x347/0x580 fs/pnode.c:261
 propagate_mnt+0x428/0x900 fs/pnode.c:319
 attach_recursive_mnt+0x787/0x1ef0 fs/namespace.c:2093
 graft_tree fs/namespace.c:2201 [inline]
 do_loopback fs/namespace.c:2329 [inline]
 do_mount+0x1aae/0x28c0 fs/namespace.c:3166
 ksys_mount+0xc2/0xf0 fs/namespace.c:3381
 __do_sys_mount fs/namespace.c:3395 [inline]
 __se_sys_mount fs/namespace.c:3392 [inline]
 __x64_sys_mount+0xb1/0xc0 fs/namespace.c:3392
 do_syscall_64+0xcb/0x150 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Freed by task 16:
 save_stack mm/kasan/common.c:69 [inline]
 set_track mm/kasan/common.c:77 [inline]
 kasan_set_free_info mm/kasan/common.c:332 [inline]
 __kasan_slab_free+0x181/0x230 mm/kasan/common.c:471
 slab_free_hook mm/slub.c:1443 [inline]
 slab_free_freelist_hook+0xd0/0x150 mm/slub.c:1476
 slab_free mm/slub.c:3041 [inline]
 kmem_cache_free+0xac/0x600 mm/slub.c:3057
 __rcu_reclaim kernel/rcu/rcu.h:222 [inline]
 rcu_do_batch kernel/rcu/tree.c:2158 [inline]
 rcu_core+0xbf0/0x1360 kernel/rcu/tree.c:2378
 __do_softirq+0x2d5/0x725 kernel/softirq.c:292

The buggy address belongs to the object at ffff88813a0b3180
 which belongs to the cache mnt_cache of size 352
The buggy address is located 8 bytes inside of
 352-byte region [ffff88813a0b3180, ffff88813a0b32e0)
The buggy address belongs to the page:
page:ffffea0004e82c80 refcount:1 mapcount:0 mapping:ffff8881da8eea00 index:0x0 compound_mapcount: 0
flags: 0x8000000000010200(slab|head)
raw: 8000000000010200 dead000000000100 dead000000000122 ffff8881da8eea00
raw: 0000000000000000 0000000000120012 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88813a0b3080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88813a0b3100: fb fb fb fb fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88813a0b3180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                      ^
 ffff88813a0b3200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88813a0b3280: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
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