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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 ffff888056621040 by task syz-executor.2/12125

CPU: 1 PID: 12125 Comm: syz-executor.2 Not tainted 4.14.262-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x1b2/0x281 lib/dump_stack.c:58
 print_address_description.cold+0x54/0x1d3 mm/kasan/report.c:252
 kasan_report_error.cold+0x8a/0x191 mm/kasan/report.c:351
 kasan_report mm/kasan/report.c:409 [inline]
 __asan_report_load4_noabort+0x68/0x70 mm/kasan/report.c:429
 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:1349
 l2tp_udp_encap_destroy+0x8d/0xf0 net/l2tp/l2tp_core.c:1375
 udpv6_destroy_sock+0xf5/0x190 net/ipv6/udp.c:1447
 sk_common_release+0x64/0x2c0 net/core/sock.c:3035
 inet_release+0xdf/0x1b0 net/ipv4/af_inet.c:425
 inet6_release+0x4c/0x70 net/ipv6/af_inet6.c:450
 __sock_release+0xcd/0x2b0 net/socket.c:602
 sock_close+0x15/0x20 net/socket.c:1139
 __fput+0x25f/0x7a0 fs/file_table.c:210
 task_work_run+0x11f/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
RIP: 0033:0x7f408cbbac2b
RSP: 002b:00007fff1e177f30 EFLAGS: 00000293 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 0000000000000014 RCX: 00007f408cbbac2b
RDX: 0000001b2ee20000 RSI: 0000001b2ee22e74 RDI: 0000000000000013
RBP: 00007f408cd1c960 R08: 0000000000000000 R09: 000000004ba12e9f
R10: 001e02ff83e14a40 R11: 0000000000000293 R12: 000000000002c30d
R13: 00007fff1e178030 R14: 00007fff1e178050 R15: 0000000000000032

Allocated by task 12128:
 save_stack mm/kasan/kasan.c:447 [inline]
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_kmalloc+0xeb/0x160 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+0x8a/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 12128:
 save_stack mm/kasan/kasan.c:447 [inline]
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_slab_free+0xc3/0x1a0 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+0x458/0x7e0 fs/inode.c:1551
 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+0x11f/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 ffff888056621040
 which belongs to the cache sock_inode_cache of size 1000
The buggy address is located 0 bytes inside of
 1000-byte region [ffff888056621040, ffff888056621428)
The buggy address belongs to the page:
page:ffffea0001598840 count:1 mapcount:0 mapping:ffff888056621040 index:0xffff888056621ffd
flags: 0xfff00000000100(slab)
raw: 00fff00000000100 ffff888056621040 ffff888056621ffd 0000000100000003
raw: ffffea0001598b60 ffffea0001598f20 ffff8880b553b900 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff888056620f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888056620f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff888056621000: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
                                           ^
 ffff888056621080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888056621100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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EXT4-fs (loop3): mounted filesystem without journal. Opts: ,errors=continue