Hello,

syzbot hit the following crash on net-next commit
5d1365940a68dd57b031b6e3c07d7d451cd69daf (Thu Apr 12 18:09:05 2018 +0000)
Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net
syzbot dashboard link: https://syzkaller.appspot.com/bug?extid=d64b64afc55660106556


So far this crash happened 5 times on net-next, upstream.
C reproducer: https://syzkaller.appspot.com/x/repro.c?id=6319968803094528
syzkaller reproducer: https://syzkaller.appspot.com/x/repro.syz?id=6099825221173248 Raw console output: https://syzkaller.appspot.com/x/log.txt?id=4953018151731200 Kernel config: https://syzkaller.appspot.com/x/.config?id=-5947642240294114534
compiler: gcc (GCC) 8.0.1 20180413 (experimental)

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Reported-by: syzbot+d64b64afc55660106...@syzkaller.appspotmail.com
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Failed to remove local publication {0,0,0}/206417777
IPVS: ftp: loaded support on port[0] = 21
IPVS: ftp: loaded support on port[0] = 21
IPVS: ftp: loaded support on port[0] = 21
==================================================================
BUG: KASAN: use-after-free in tipc_service_delete net/tipc/name_table.c:751 [inline] BUG: KASAN: use-after-free in tipc_nametbl_stop+0x94e/0xd70 net/tipc/name_table.c:780
Read of size 8 at addr ffff8801c4c25130 by task kworker/u4:2/30

CPU: 0 PID: 30 Comm: kworker/u4:2 Not tainted 4.16.0+ #1
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: netns cleanup_net
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+0x242/0x2fe mm/kasan/report.c:412
 __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433
 tipc_service_delete net/tipc/name_table.c:751 [inline]
 tipc_nametbl_stop+0x94e/0xd70 net/tipc/name_table.c:780
 tipc_exit_net+0x2d/0x40 net/tipc/core.c:103
 ops_exit_list.isra.7+0xb0/0x160 net/core/net_namespace.c:152
 cleanup_net+0x51d/0xb20 net/core/net_namespace.c:523
 process_one_work+0xc1e/0x1b50 kernel/workqueue.c:2145
 worker_thread+0x1cc/0x1440 kernel/workqueue.c:2279
 kthread+0x345/0x410 kernel/kthread.c:238
 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:411

Allocated by task 4535:
 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]
 kzalloc include/linux/slab.h:701 [inline]
 tipc_service_create_range net/tipc/name_table.c:183 [inline]
 tipc_service_insert_publ net/tipc/name_table.c:207 [inline]
 tipc_nametbl_insert_publ+0x569/0x1910 net/tipc/name_table.c:371
 tipc_nametbl_publish+0x6c3/0xba0 net/tipc/name_table.c:618
 tipc_sk_publish+0x22a/0x510 net/tipc/socket.c:2604
 tipc_bind+0x206/0x330 net/tipc/socket.c:647
 __sys_bind+0x331/0x440 net/socket.c:1484
 SYSC_bind net/socket.c:1495 [inline]
 SyS_bind+0x24/0x30 net/socket.c:1493
 do_syscall_64+0x29e/0x9d0 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x42/0xb7

Freed by task 30:
 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_service_remove_publ.isra.8+0x909/0xc30 net/tipc/name_table.c:283
 tipc_service_delete net/tipc/name_table.c:753 [inline]
 tipc_nametbl_stop+0x746/0xd70 net/tipc/name_table.c:780
 tipc_exit_net+0x2d/0x40 net/tipc/core.c:103
 ops_exit_list.isra.7+0xb0/0x160 net/core/net_namespace.c:152
 cleanup_net+0x51d/0xb20 net/core/net_namespace.c:523
 process_one_work+0xc1e/0x1b50 kernel/workqueue.c:2145
 worker_thread+0x1cc/0x1440 kernel/workqueue.c:2279
 kthread+0x345/0x410 kernel/kthread.c:238
 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:411

The buggy address belongs to the object at ffff8801c4c25100
 which belongs to the cache kmalloc-64 of size 64
The buggy address is located 48 bytes inside of
 64-byte region [ffff8801c4c25100, ffff8801c4c25140)
The buggy address belongs to the page:
page:ffffea0007130940 count:1 mapcount:0 mapping:ffff8801c4c25000 index:0x0
flags: 0x2fffc0000000100(slab)
raw: 02fffc0000000100 ffff8801c4c25000 0000000000000000 0000000100000020
raw: ffffea0006ccf860 ffffea00070840a0 ffff8801dac00340 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801c4c25000: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
 ffff8801c4c25080: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
ffff8801c4c25100: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
                                     ^
 ffff8801c4c25180: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
 ffff8801c4c25200: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
==================================================================


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