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BUG: KASAN: use-after-free in inet_create+0xd9c/0xf50 net/ipv4/af_inet.c:339
Read of size 4 at addr ffff88018f8a0944 by task kworker/u4:1/22

CPU: 0 PID: 22 Comm: kworker/u4:1 Not tainted 4.16.0+ #15
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: krdsd rds_connect_worker
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x1a7/0x27d lib/dump_stack.c:53
IPVS: ftp: loaded support on port[0] = 21
 print_address_description+0x73/0x250 mm/kasan/report.c:256
 kasan_report_error mm/kasan/report.c:354 [inline]
 kasan_report+0x23c/0x360 mm/kasan/report.c:412
 __asan_report_load4_noabort+0x14/0x20 mm/kasan/report.c:432
 inet_create+0xd9c/0xf50 net/ipv4/af_inet.c:339
 __sock_create+0x4d4/0x850 net/socket.c:1285
 sock_create_kern+0x3f/0x50 net/socket.c:1331
 rds_tcp_conn_path_connect+0x284/0x950 net/rds/tcp_connect.c:108
 rds_connect_worker+0x166/0x210 net/rds/threads.c:175
 process_one_work+0xc97/0x1c40 kernel/workqueue.c:2145
 worker_thread+0x1c3/0x1380 kernel/workqueue.c:2279
 kthread+0x33c/0x400 kernel/kthread.c:238
 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:411

Allocated by task 8136:
 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:552
 kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:489
 kmem_cache_alloc+0x12e/0x760 mm/slab.c:3542
 kmem_cache_zalloc include/linux/slab.h:691 [inline]
 net_alloc net/core/net_namespace.c:383 [inline]
 copy_net_ns+0x152/0x480 net/core/net_namespace.c:423
 create_new_namespaces+0x432/0x890 kernel/nsproxy.c:107
 unshare_nsproxy_namespaces+0xae/0x1e0 kernel/nsproxy.c:206
 ksys_unshare+0x68a/0xe90 kernel/fork.c:2407
 SYSC_unshare kernel/fork.c:2475 [inline]
 SyS_unshare+0x15/0x20 kernel/fork.c:2473
 do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x42/0xb7

Freed by task 22:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459 [inline]
 __kasan_slab_free+0x11a/0x170 mm/kasan/kasan.c:520
 kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:527
 __cache_free mm/slab.c:3486 [inline]
 kmem_cache_free+0x83/0x2a0 mm/slab.c:3744
 net_free net/core/net_namespace.c:399 [inline]
 net_drop_ns.part.13+0x10c/0x130 net/core/net_namespace.c:406
 net_drop_ns net/core/net_namespace.c:405 [inline]
 cleanup_net+0x7a6/0xaa0 net/core/net_namespace.c:541
 process_one_work+0xc97/0x1c40 kernel/workqueue.c:2145
 worker_thread+0x1c3/0x1380 kernel/workqueue.c:2279
 kthread+0x33c/0x400 kernel/kthread.c:238
 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:411

The buggy address belongs to the object at ffff88018f8a0240
 which belongs to the cache net_namespace of size 8768
The buggy address is located 1796 bytes inside of
 8768-byte region [ffff88018f8a0240, ffff88018f8a2480)
The buggy address belongs to the page:
page:ffffea00063e2800 count:1 mapcount:0 mapping:ffff88018f8a0240 index:0x0 compound_mapcount: 0
flags: 0x2fffc0000008100(slab|head)
raw: 02fffc0000008100 ffff88018f8a0240 0000000000000000 0000000100000001
raw: ffffea0007620b20 ffffea0006220720 ffff8801d9fbfe00 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88018f8a0800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88018f8a0880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88018f8a0900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                           ^
 ffff88018f8a0980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88018f8a0a00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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