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BUG: KASAN: use-after-free in __hlist_del include/linux/list.h:773 [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+0x2ad/0x460 kernel/time/timer.c:1238
Write of size 8 at addr ffff8881daa6b1c8 by task syz-executor.5/5975

CPU: 1 PID: 5975 Comm: syz-executor.5 Not tainted 5.4.190-syzkaller-00034-gc79dfbc288c5 #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+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_del include/linux/list.h:773 [inline]
 detach_timer kernel/time/timer.c:824 [inline]
 detach_if_pending kernel/time/timer.c:841 [inline]
 try_to_del_timer_sync+0x2ad/0x460 kernel/time/timer.c:1238
 del_timer_sync+0x74/0xd0 kernel/time/timer.c:1379
 tun_flow_uninit drivers/net/tun.c:1387 [inline]
 tun_free_netdev+0x99/0x3b0 drivers/net/tun.c:2328
 netdev_run_todo+0xa3c/0xc80 net/core/dev.c:9445
 tun_detach drivers/net/tun.c:751 [inline]
 tun_chr_close+0xc0/0xd0 drivers/net/tun.c:3523
 __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: 0033:0x7f64d00d8d4b
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:00007ffe7b9cf360 EFLAGS: 00000293 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 0000000000000005 RCX: 00007f64d00d8d4b
RDX: 0000000000000000 RSI: 00007f64d009d000 RDI: 0000000000000004
RBP: 00007f64d023a960 R08: 0000000000000000 R09: 00000000742a82f4
R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000017484
R13: 00007ffe7b9cf460 R14: 00007ffe7b9cf480 R15: 0000000000000032

Allocated by task 2625:
 save_stack mm/kasan/common.c:70 [inline]
 set_track mm/kasan/common.c:78 [inline]
 __kasan_kmalloc+0x131/0x1e0 mm/kasan/common.c:529
 slab_post_alloc_hook mm/slab.h:584 [inline]
 slab_alloc_node mm/slub.c:2829 [inline]
 slab_alloc mm/slub.c:2837 [inline]
 kmem_cache_alloc+0xd0/0x210 mm/slub.c:2842
 shmem_alloc_inode+0x16/0x30 mm/shmem.c:3699
 alloc_inode fs/inode.c:232 [inline]
 new_inode_pseudo+0x60/0x210 fs/inode.c:928
 new_inode+0x25/0x1d0 fs/inode.c:957
 shmem_get_inode+0x113/0x630 mm/shmem.c:2252
 shmem_symlink+0xc1/0x520 mm/shmem.c:3068
 vfs_symlink+0x369/0x500 fs/namei.c:4206
 do_symlinkat+0x133/0x340 fs/namei.c:4233
 do_syscall_64+0xcb/0x1c0 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Freed by task 9:
 save_stack mm/kasan/common.c:70 [inline]
 set_track mm/kasan/common.c:78 [inline]
 kasan_set_free_info mm/kasan/common.c:345 [inline]
 __kasan_slab_free+0x178/0x240 mm/kasan/common.c:487
 slab_free_hook mm/slub.c:1455 [inline]
 slab_free_freelist_hook+0x80/0x150 mm/slub.c:1494
 slab_free mm/slub.c:3080 [inline]
 kmem_cache_free+0xa9/0x1d0 mm/slub.c:3096
 __rcu_reclaim kernel/rcu/rcu.h:222 [inline]
 rcu_do_batch+0x41c/0x910 kernel/rcu/tree.c:2167
 rcu_core+0x448/0xbc0 kernel/rcu/tree.c:2387
 __do_softirq+0x23e/0x643 kernel/softirq.c:292

The buggy address belongs to the object at ffff8881daa6afb0
 which belongs to the cache shmem_inode_cache of size 744
The buggy address is located 536 bytes inside of
 744-byte region [ffff8881daa6afb0, ffff8881daa6b298)
The buggy address belongs to the page:
page:ffffea00076a9a00 refcount:1 mapcount:0 mapping:ffff8881f5d41180 index:0x0 compound_mapcount: 0
flags: 0x8000000000010200(slab|head)
raw: 8000000000010200 dead000000000100 dead000000000122 ffff8881f5d41180
raw: 0000000000000000 0000000000120012 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 2, migratetype Unmovable, gfp_mask 0x1d20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_HARDWALL)
 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_slab_page+0x39/0x3e0 mm/slub.c:343
 allocate_slab mm/slub.c:1683 [inline]
 new_slab+0x97/0x450 mm/slub.c:1749
 new_slab_objects mm/slub.c:2506 [inline]
 ___slab_alloc+0x320/0x4b0 mm/slub.c:2667
 __slab_alloc+0x5a/0x90 mm/slub.c:2707
 slab_alloc_node mm/slub.c:2792 [inline]
 slab_alloc mm/slub.c:2837 [inline]
 kmem_cache_alloc+0x100/0x210 mm/slub.c:2842
 shmem_alloc_inode+0x16/0x30 mm/shmem.c:3699
 alloc_inode fs/inode.c:232 [inline]
 new_inode_pseudo+0x60/0x210 fs/inode.c:928
 new_inode+0x25/0x1d0 fs/inode.c:957
 shmem_get_inode+0x113/0x630 mm/shmem.c:2252
 shmem_symlink+0xc1/0x520 mm/shmem.c:3068
 vfs_symlink+0x369/0x500 fs/namei.c:4206
 do_symlinkat+0x133/0x340 fs/namei.c:4233
 do_syscall_64+0xcb/0x1c0 arch/x86/entry/common.c:290
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
 device_release+0x70/0x1a0 drivers/base/core.c:1776
 kobject_cleanup lib/kobject.c:708 [inline]
 kobject_release+0x1f3/0x3d0 lib/kobject.c:739
 tun_set_iff+0xc0b/0x1050 drivers/net/tun.c:2906
 __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

Memory state around the buggy address:
 ffff8881daa6b080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8881daa6b100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff8881daa6b180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                              ^
 ffff8881daa6b200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8881daa6b280: fb fb fb fc fc fc fc fc fc fc fc fc fc fc fc fc
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