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BUG: KASAN: use-after-free in inet_shutdown+0x2c0/0x340 net/ipv4/af_inet.c:816
Read of size 4 at addr ffff88805244e0c0 by task kworker/u4:5/7717

CPU: 1 PID: 7717 Comm: kworker/u4:5 Not tainted 4.14.184-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: l2tp l2tp_tunnel_del_work
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x1b2/0x283 lib/dump_stack.c:58
 print_address_description.cold+0x54/0x1dc mm/kasan/report.c:252
 kasan_report_error mm/kasan/report.c:351 [inline]
 kasan_report mm/kasan/report.c:409 [inline]
 kasan_report.cold+0xa9/0x2b9 mm/kasan/report.c:393
 inet_shutdown+0x2c0/0x340 net/ipv4/af_inet.c:816
 pppol2tp_session_close+0x8f/0xe0 net/l2tp/l2tp_ppp.c:449
 l2tp_tunnel_closeall+0x235/0x370 net/l2tp/l2tp_core.c:1350
 l2tp_tunnel_del_work+0x62/0x400 net/l2tp/l2tp_core.c:1390
 process_one_work+0x7c0/0x14c0 kernel/workqueue.c:2116
 worker_thread+0x5d7/0x1080 kernel/workqueue.c:2250
 kthread+0x30d/0x420 kernel/kthread.c:232
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404

Allocated by task 22748:
 save_stack mm/kasan/kasan.c:447 [inline]
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_kmalloc.part.0+0x4f/0xd0 mm/kasan/kasan.c:551
 kmem_cache_alloc+0x124/0x3c0 mm/slab.c:3552
 sock_alloc_inode+0x19/0x250 net/socket.c:251
 alloc_inode+0x5d/0x170 fs/inode.c:210
 new_inode_pseudo+0x14/0xe0 fs/inode.c:899
 sock_alloc+0x3c/0x270 net/socket.c:569
 __sock_create+0x89/0x620 net/socket.c:1239
 sock_create net/socket.c:1315 [inline]
 SYSC_socket net/socket.c:1345 [inline]
 SyS_socket+0xd1/0x1b0 net/socket.c:1325
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb

Freed by task 22751:
 save_stack mm/kasan/kasan.c:447 [inline]
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_slab_free+0xaf/0x190 mm/kasan/kasan.c:524
 __cache_free mm/slab.c:3496 [inline]
 kmem_cache_free+0x7c/0x2b0 mm/slab.c:3758
 destroy_inode+0xb9/0x110 fs/inode.c:267
 iput_final fs/inode.c:1524 [inline]
 iput fs/inode.c:1551 [inline]
 iput+0x457/0x8d0 fs/inode.c:1536
 dentry_unlink_inode+0x25c/0x310 fs/dcache.c:387
 __dentry_kill+0x320/0x550 fs/dcache.c:591
 dentry_kill fs/dcache.c:632 [inline]
 dput.part.0+0x56f/0x710 fs/dcache.c:847
 dput+0x1b/0x30 fs/dcache.c:811
 __fput+0x445/0x7a0 fs/file_table.c:228
 task_work_run+0x113/0x190 kernel/task_work.c:113
 tracehook_notify_resume include/linux/tracehook.h:191 [inline]
 exit_to_usermode_loop+0x1ad/0x200 arch/x86/entry/common.c:164
 prepare_exit_to_usermode arch/x86/entry/common.c:199 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:270 [inline]
 do_syscall_64+0x4a3/0x640 arch/x86/entry/common.c:297
 entry_SYSCALL_64_after_hwframe+0x46/0xbb

The buggy address belongs to the object at ffff88805244e0c0
 which belongs to the cache sock_inode_cache of size 1000
The buggy address is located 0 bytes inside of
 1000-byte region [ffff88805244e0c0, ffff88805244e4a8)
The buggy address belongs to the page:
page:ffffea0001491380 count:1 mapcount:0 mapping:ffff88805244e0c0 index:0xffff88805244effd
flags: 0xfffe0000000100(slab)
raw: 00fffe0000000100 ffff88805244e0c0 ffff88805244effd 0000000100000003
raw: ffffea0001498060 ffffea000207d860 ffff8880a9e0f900 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88805244df80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88805244e000: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88805244e080: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
                                           ^
 ffff88805244e100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88805244e180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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