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BUG: KASAN: use-after-free in __fput+0x6b1/0x7f0 fs/file_table.c:212
Read of size 2 at addr ffff8801937d4170 by task syz-executor5/15400

CPU: 1 PID: 15400 Comm: syz-executor5 Not tainted 4.14.0-mm1+ #25
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+0x194/0x257 lib/dump_stack.c:53
 print_address_description+0x73/0x250 mm/kasan/report.c:252
 kasan_report_error mm/kasan/report.c:351 [inline]
 kasan_report+0x25b/0x340 mm/kasan/report.c:409
 __asan_report_load2_noabort+0x14/0x20 mm/kasan/report.c:428
 __fput+0x6b1/0x7f0 fs/file_table.c:212
 ____fput+0x15/0x20 fs/file_table.c:244
 task_work_run+0x199/0x270 kernel/task_work.c:113
 get_signal+0x133d/0x16c0 kernel/signal.c:2165
 do_signal+0x94/0x1ee0 arch/x86/kernel/signal.c:809
 exit_to_usermode_loop+0x214/0x310 arch/x86/entry/common.c:158
 prepare_exit_to_usermode arch/x86/entry/common.c:195 [inline]
 syscall_return_slowpath+0x490/0x550 arch/x86/entry/common.c:264
 entry_SYSCALL_64_fastpath+0x94/0x96
RIP: 0033:0x452879
RSP: 002b:00007f34382c3be8 EFLAGS: 00000212 ORIG_RAX: 0000000000000010
RAX: fffffffffffffff4 RBX: 0000000000758020 RCX: 0000000000452879
RDX: 0000000020c98ffc RSI: 00000000000089e2 RDI: 0000000000000015
RBP: 0000000000000349 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000212 R12: 00000000006f1f78
R13: 0000000000000016 R14: 00007f34382c46d4 R15: ffffffffffffffff

Allocated by task 15400:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_kmalloc+0xad/0xe0 mm/kasan/kasan.c:551
 kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:489
 kmem_cache_alloc+0x12e/0x760 mm/slab.c:3548
 sock_alloc_inode+0x70/0x300 net/socket.c:250
 alloc_inode+0x65/0x180 fs/inode.c:208
 new_inode_pseudo+0x69/0x190 fs/inode.c:889
 sock_alloc+0x41/0x270 net/socket.c:565
 kcm_clone net/kcm/kcmsock.c:1637 [inline]
 kcm_ioctl+0x864/0x1610 net/kcm/kcmsock.c:1713
 sock_do_ioctl+0x65/0xb0 net/socket.c:960
 sock_ioctl+0x2c2/0x440 net/socket.c:1057
 vfs_ioctl fs/ioctl.c:46 [inline]
 do_vfs_ioctl+0x1b1/0x1530 fs/ioctl.c:686
 SYSC_ioctl fs/ioctl.c:701 [inline]
 SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692
 entry_SYSCALL_64_fastpath+0x1f/0x96

Freed by task 15400:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_slab_free+0x71/0xc0 mm/kasan/kasan.c:524
 __cache_free mm/slab.c:3492 [inline]
 kmem_cache_free+0x77/0x280 mm/slab.c:3750
 sock_destroy_inode+0x56/0x70 net/socket.c:280
 destroy_inode+0x15d/0x200 fs/inode.c:265
 evict+0x57e/0x920 fs/inode.c:569
 iput_final fs/inode.c:1514 [inline]
 iput+0x7b9/0xaf0 fs/inode.c:1541
 sock_release+0x168/0x1e0 net/socket.c:606
 sock_close+0x16/0x20 net/socket.c:1125
 __fput+0x333/0x7f0 fs/file_table.c:210
 ____fput+0x15/0x20 fs/file_table.c:244
 task_work_run+0x199/0x270 kernel/task_work.c:113
 get_signal+0x133d/0x16c0 kernel/signal.c:2165
 do_signal+0x94/0x1ee0 arch/x86/kernel/signal.c:809
 exit_to_usermode_loop+0x214/0x310 arch/x86/entry/common.c:158
 prepare_exit_to_usermode arch/x86/entry/common.c:195 [inline]
 syscall_return_slowpath+0x490/0x550 arch/x86/entry/common.c:264
 entry_SYSCALL_64_fastpath+0x94/0x96

The buggy address belongs to the object at ffff8801937d4140
 which belongs to the cache sock_inode_cache of size 1048
The buggy address is located 48 bytes inside of
 1048-byte region [ffff8801937d4140, ffff8801937d4558)
The buggy address belongs to the page:
page:ffffea00064df500 count:1 mapcount:0 mapping:ffff8801937d4140 index:0xffff8801937d4ffd
flags: 0x2fffc0000000100(slab)
raw: 02fffc0000000100 ffff8801937d4140 ffff8801937d4ffd 0000000100000003
raw: ffffea00064df020 ffffea00064df560 ffff8801d9d1c500 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801937d4000: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8801937d4080: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff8801937d4100: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
                                                             ^
 ffff8801937d4180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8801937d4200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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