Hello,

syzbot hit the following crash on upstream commit
b284d4d5a6785f8cd07eda2646a95782373cd01e (Tue Apr 10 19:25:30 2018 +0000)
Merge tag 'ceph-for-4.17-rc1' of git://github.com/ceph/ceph-client
syzbot dashboard link: https://syzkaller.appspot.com/bug?extid=aa245f26d42b8305d157


So far this crash happened 2 times on upstream.
C reproducer: https://syzkaller.appspot.com/x/repro.c?id=5881855630901248
syzkaller reproducer: https://syzkaller.appspot.com/x/repro.syz?id=5979790213382144 Raw console output: https://syzkaller.appspot.com/x/log.txt?id=5808961445953536 Kernel config: https://syzkaller.appspot.com/x/.config?id=-1223000601505858474
compiler: gcc (GCC) 8.0.1 20180301 (experimental)

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Reported-by: syzbot+aa245f26d42b8305d...@syzkaller.appspotmail.com
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R10: 0000000020b89fe4 R11: 0000000000000246 R12: 0000000000000005
R13: ffffffffffffffff R14: 0000000000000000 R15: 0000000000000000
Service creation failed, no memory
Failed to subscribe for {1906,0,4294967295}
==================================================================
BUG: KASAN: use-after-free in tipc_sub_unsubscribe+0x22d/0x305 net/tipc/subscr.c:167
Read of size 4 at addr ffff8801b78718d8 by task syzkaller446011/4466

CPU: 1 PID: 4466 Comm: syzkaller446011 Not tainted 4.16.0+ #19
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+0x1b9/0x294 lib/dump_stack.c:113
 print_address_description+0x6c/0x20b mm/kasan/report.c:256
 kasan_report_error mm/kasan/report.c:354 [inline]
 kasan_report.cold.7+0xac/0x2f5 mm/kasan/report.c:412
 __asan_report_load4_noabort+0x14/0x20 mm/kasan/report.c:432
 tipc_sub_unsubscribe+0x22d/0x305 net/tipc/subscr.c:167
 tipc_conn_delete_sub+0x32d/0x530 net/tipc/topsrv.c:245
 tipc_topsrv_kern_unsubscr+0x280/0x3f0 net/tipc/topsrv.c:598
 tipc_group_delete+0x2dd/0x3f0 net/tipc/group.c:231
 tipc_sk_leave+0x10e/0x210 net/tipc/socket.c:2800
 tipc_release+0x146/0x1290 net/tipc/socket.c:576
 sock_release+0x96/0x1b0 net/socket.c:594
 sock_close+0x16/0x20 net/socket.c:1149
 __fput+0x34d/0x890 fs/file_table.c:209
 ____fput+0x15/0x20 fs/file_table.c:243
 task_work_run+0x1e4/0x290 kernel/task_work.c:113
 exit_task_work include/linux/task_work.h:22 [inline]
 do_exit+0x1aee/0x2730 kernel/exit.c:865
 do_group_exit+0x16f/0x430 kernel/exit.c:968
 SYSC_exit_group kernel/exit.c:979 [inline]
 SyS_exit_group+0x1d/0x20 kernel/exit.c:977
 do_syscall_64+0x29e/0x9d0 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x43f1f8
RSP: 002b:00007fff7867bac8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043f1f8
RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000
RBP: 00000000004bf2e8 R08: 00000000000000e7 R09: ffffffffffffffd0
R10: 0000000020b89fe4 R11: 0000000000000246 R12: 0000000000000001
R13: 00000000006d1180 R14: 0000000000000000 R15: 0000000000000000

Allocated by task 4466:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:448
 set_track mm/kasan/kasan.c:460 [inline]
 kasan_kmalloc+0xc4/0xe0 mm/kasan/kasan.c:553
 kmem_cache_alloc_trace+0x152/0x780 mm/slab.c:3620
 kmalloc include/linux/slab.h:512 [inline]
 tipc_sub_subscribe+0x25a/0x6b0 net/tipc/subscr.c:143
 tipc_conn_rcv_sub.isra.5+0x42c/0x7e0 net/tipc/topsrv.c:381
 tipc_topsrv_kern_subscr+0x72b/0xad0 net/tipc/topsrv.c:582
 tipc_group_create+0x72e/0xa50 net/tipc/group.c:194
 tipc_sk_join net/tipc/socket.c:2766 [inline]
 tipc_setsockopt+0x2c9/0xd70 net/tipc/socket.c:2881
 __sys_setsockopt+0x1bd/0x390 net/socket.c:1903
 SYSC_setsockopt net/socket.c:1914 [inline]
 SyS_setsockopt+0x34/0x50 net/socket.c:1911
 do_syscall_64+0x29e/0x9d0 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x42/0xb7

Freed by task 4466:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:448
 set_track mm/kasan/kasan.c:460 [inline]
 __kasan_slab_free+0x11a/0x170 mm/kasan/kasan.c:521
 kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528
 __cache_free mm/slab.c:3498 [inline]
 kfree+0xd9/0x260 mm/slab.c:3813
 tipc_sub_kref_release net/tipc/subscr.c:117 [inline]
 kref_put include/linux/kref.h:70 [inline]
 tipc_sub_put+0x33/0x40 net/tipc/subscr.c:122
 tipc_nametbl_unsubscribe+0x52c/0xaf0 net/tipc/name_table.c:709
 tipc_sub_unsubscribe+0x6d/0x305 net/tipc/subscr.c:166
 tipc_conn_delete_sub+0x32d/0x530 net/tipc/topsrv.c:245
 tipc_topsrv_kern_unsubscr+0x280/0x3f0 net/tipc/topsrv.c:598
 tipc_group_delete+0x2dd/0x3f0 net/tipc/group.c:231
 tipc_sk_leave+0x10e/0x210 net/tipc/socket.c:2800
 tipc_release+0x146/0x1290 net/tipc/socket.c:576
 sock_release+0x96/0x1b0 net/socket.c:594
 sock_close+0x16/0x20 net/socket.c:1149
 __fput+0x34d/0x890 fs/file_table.c:209
 ____fput+0x15/0x20 fs/file_table.c:243
 task_work_run+0x1e4/0x290 kernel/task_work.c:113
 exit_task_work include/linux/task_work.h:22 [inline]
 do_exit+0x1aee/0x2730 kernel/exit.c:865
 do_group_exit+0x16f/0x430 kernel/exit.c:968
 SYSC_exit_group kernel/exit.c:979 [inline]
 SyS_exit_group+0x1d/0x20 kernel/exit.c:977
 do_syscall_64+0x29e/0x9d0 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x42/0xb7

The buggy address belongs to the object at ffff8801b7871840
 which belongs to the cache kmalloc-256 of size 256
The buggy address is located 152 bytes inside of
 256-byte region [ffff8801b7871840, ffff8801b7871940)
The buggy address belongs to the page:
page:ffffea0006de1c40 count:1 mapcount:0 mapping:ffff8801b78710c0 index:0x0
flags: 0x2fffc0000000100(slab)
raw: 02fffc0000000100 ffff8801b78710c0 0000000000000000 000000010000000c
raw: ffffea00071ce1a0 ffffea0006db8fa0 ffff8801dac007c0 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801b7871780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8801b7871800: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
ffff8801b7871880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                    ^
 ffff8801b7871900: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
 ffff8801b7871980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


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