==================================================================
BUG: KASAN: use-after-free in inet_shutdown+0x2e9/0x370 net/ipv4/af_inet.c:809
Read of size 4 at addr ffff8800ba386200 by task syz-executor7/18634

CPU: 0 PID: 18634 Comm: syz-executor7 Not tainted 4.4.147-ga5fc665 #16
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 0000000000000000 ebe28daf8f365697 ffff8801bc327b58 ffffffff81e12a4d
 ffffea0002e8e100 ffff8800ba386200 0000000000000000 ffff8800ba386200
 ffff8800b18aa7d8 ffff8801bc327b90 ffffffff81517fd6 ffff8800ba386200
Call Trace:
 [<ffffffff81e12a4d>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81e12a4d>] dump_stack+0xc1/0x124 lib/dump_stack.c:51
 [<ffffffff81517fd6>] print_address_description+0x6c/0x216 mm/kasan/report.c:252
 [<ffffffff815182f5>] kasan_report_error mm/kasan/report.c:351 [inline]
 [<ffffffff815182f5>] kasan_report.cold.7+0x175/0x2f7 mm/kasan/report.c:408
 [<ffffffff814fbdc4>] __asan_report_load4_noabort+0x14/0x20 mm/kasan/report.c:428
 [<ffffffff832fe919>] inet_shutdown+0x2e9/0x370 net/ipv4/af_inet.c:809
 [<ffffffff835ac840>] pppol2tp_session_close+0xa0/0xe0 net/l2tp/l2tp_ppp.c:458
 [<ffffffff835a58b5>] l2tp_tunnel_closeall+0x205/0x350 net/l2tp/l2tp_core.c:1274
 [<ffffffff835a647b>] l2tp_udp_encap_destroy+0x8b/0xf0 net/l2tp/l2tp_core.c:1300
 [<ffffffff83498481>] udpv6_destroy_sock+0xb1/0xd0 net/ipv6/udp.c:1421
 [<ffffffff82f3516d>] sk_common_release+0x6d/0x300 net/core/sock.c:2680
 [<ffffffff83497135>] udp_lib_close+0x15/0x20 include/net/udp.h:190
 [<ffffffff832fea9f>] inet_release+0xff/0x1d0 net/ipv4/af_inet.c:435
 [<ffffffff83421730>] inet6_release+0x50/0x70 net/ipv6/af_inet6.c:424
 [<ffffffff82f1f876>] sock_release+0x96/0x1c0 net/socket.c:587
 [<ffffffff82f1f9b6>] sock_close+0x16/0x20 net/socket.c:1038
 [<ffffffff815253c5>] __fput+0x235/0x6f0 fs/file_table.c:208
 [<ffffffff81525905>] ____fput+0x15/0x20 fs/file_table.c:244
 [<ffffffff8118e00f>] task_work_run+0x10f/0x190 kernel/task_work.c:115
 [<ffffffff8100362d>] tracehook_notify_resume include/linux/tracehook.h:191 [inline]
 [<ffffffff8100362d>] exit_to_usermode_loop+0x13d/0x160 arch/x86/entry/common.c:253
 [<ffffffff8100708e>] prepare_exit_to_usermode arch/x86/entry/common.c:284 [inline]
 [<ffffffff8100708e>] syscall_return_slowpath arch/x86/entry/common.c:349 [inline]
 [<ffffffff8100708e>] do_syscall_32_irqs_on arch/x86/entry/common.c:399 [inline]
 [<ffffffff8100708e>] do_fast_syscall_32+0x61e/0x8b0 arch/x86/entry/common.c:460
 [<ffffffff838ca5c3>] sysenter_flags_fixed+0xd/0x1a

Allocated by task 18634:
 [<ffffffff81034676>] save_stack_trace+0x26/0x50 arch/x86/kernel/stacktrace.c:63
 [<ffffffff814fae93>] save_stack+0x43/0xd0 mm/kasan/kasan.c:512
 [<ffffffff814fb177>] set_track mm/kasan/kasan.c:524 [inline]
 [<ffffffff814fb177>] kasan_kmalloc+0xc7/0xe0 mm/kasan/kasan.c:616
 [<ffffffff814fb742>] kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:554
 [<ffffffff814f723e>] slab_post_alloc_hook mm/slub.c:1349 [inline]
 [<ffffffff814f723e>] slab_alloc_node mm/slub.c:2615 [inline]
 [<ffffffff814f723e>] slab_alloc mm/slub.c:2623 [inline]
 [<ffffffff814f723e>] kmem_cache_alloc+0xbe/0x2a0 mm/slub.c:2628
 [<ffffffff82f21e1d>] sock_alloc_inode+0x1d/0x260 net/socket.c:251
 [<ffffffff81571e23>] alloc_inode+0x63/0x180 fs/inode.c:198
 [<ffffffff81577717>] new_inode_pseudo+0x17/0xe0 fs/inode.c:878
 [<ffffffff82f200d1>] sock_alloc+0x41/0x280 net/socket.c:556
 [<ffffffff82f25b3d>] __sock_create+0x8d/0x5f0 net/socket.c:1142
 [<ffffffff82f262d0>] sock_create net/socket.c:1218 [inline]
 [<ffffffff82f262d0>] SYSC_socket net/socket.c:1248 [inline]
 [<ffffffff82f262d0>] SyS_socket+0xf0/0x1b0 net/socket.c:1228
 [<ffffffff81006d94>] do_syscall_32_irqs_on arch/x86/entry/common.c:393 [inline]
 [<ffffffff81006d94>] do_fast_syscall_32+0x324/0x8b0 arch/x86/entry/common.c:460
 [<ffffffff838ca5c3>] sysenter_flags_fixed+0xd/0x1a

Freed by task 18624:
 [<ffffffff81034676>] save_stack_trace+0x26/0x50 arch/x86/kernel/stacktrace.c:63
 [<ffffffff814fae93>] save_stack+0x43/0xd0 mm/kasan/kasan.c:512
 [<ffffffff814fb7c2>] set_track mm/kasan/kasan.c:524 [inline]
 [<ffffffff814fb7c2>] kasan_slab_free+0x72/0xc0 mm/kasan/kasan.c:589
 [<ffffffff814f894e>] slab_free_hook mm/slub.c:1383 [inline]
 [<ffffffff814f894e>] slab_free_freelist_hook mm/slub.c:1405 [inline]
 [<ffffffff814f894e>] slab_free mm/slub.c:2859 [inline]
 [<ffffffff814f894e>] kmem_cache_free+0xbe/0x340 mm/slub.c:2881
 [<ffffffff82f21de6>] sock_destroy_inode+0x56/0x70 net/socket.c:281
 [<ffffffff81574612>] destroy_inode+0xc2/0x120 fs/inode.c:255
 [<ffffffff81574992>] evict+0x322/0x4f0 fs/inode.c:559
 [<ffffffff81574fe1>] iput_final fs/inode.c:1477 [inline]
 [<ffffffff81574fe1>] iput+0x391/0x980 fs/inode.c:1504
 [<ffffffff815667f2>] dentry_iput fs/dcache.c:372 [inline]
 [<ffffffff815667f2>] __dentry_kill+0x492/0x5f0 fs/dcache.c:559
 [<ffffffff8156a0e7>] dentry_kill fs/dcache.c:603 [inline]
 [<ffffffff8156a0e7>] dput.part.26+0x587/0x760 fs/dcache.c:818
 [<ffffffff8156a2df>] dput+0x1f/0x30 fs/dcache.c:782
 [<ffffffff81525591>] __fput+0x401/0x6f0 fs/file_table.c:226
 [<ffffffff81525905>] ____fput+0x15/0x20 fs/file_table.c:244
 [<ffffffff8118e00f>] task_work_run+0x10f/0x190 kernel/task_work.c:115
 [<ffffffff81161450>] get_signal+0x1190/0x14b0 kernel/signal.c:2151
 [<ffffffff8100df4b>] do_signal+0x8b/0x1d30 arch/x86/kernel/signal.c:712
 [<ffffffff8100360a>] exit_to_usermode_loop+0x11a/0x160 arch/x86/entry/common.c:249
 [<ffffffff8100708e>] prepare_exit_to_usermode arch/x86/entry/common.c:284 [inline]
 [<ffffffff8100708e>] syscall_return_slowpath arch/x86/entry/common.c:349 [inline]
 [<ffffffff8100708e>] do_syscall_32_irqs_on arch/x86/entry/common.c:399 [inline]
 [<ffffffff8100708e>] do_fast_syscall_32+0x61e/0x8b0 arch/x86/entry/common.c:460
 [<ffffffff838ca5c3>] sysenter_flags_fixed+0xd/0x1a

The buggy address belongs to the object at ffff8800ba386200
 which belongs to the cache sock_inode_cache of size 936
The buggy address is located 0 bytes inside of
 936-byte region [ffff8800ba386200, ffff8800ba3865a8)
The buggy address belongs to the page:
------------[ cut here ]------------
WARNING: CPU: 1 PID: -2125925129 at kernel/locking/lockdep.c:3198 __lock_acquire+0x296f/0x5270 kernel/locking/lockdep.c:3198()
DEBUG_LOCKS_WARN_ON(chain_key != 0)