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BUG: KASAN: use-after-free in inet_create+0xd9a/0xf50 net/ipv4/af_inet.c:339
Read of size 4 at addr ffff8801c80da684 by task kworker/u4:6/9780

CPU: 0 PID: 9780 Comm: kworker/u4:6 Not tainted 4.15.0+ #297
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+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_load4_noabort+0x14/0x20 mm/kasan/report.c:429
 inet_create+0xd9a/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+0x277/0x940 net/rds/tcp_connect.c:108
 rds_connect_worker+0x156/0x1f0 net/rds/threads.c:175
 process_one_work+0xbbf/0x1af0 kernel/workqueue.c:2113
 worker_thread+0x223/0x1990 kernel/workqueue.c:2247
 kthread+0x33c/0x400 kernel/kthread.c:238
 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:429

Allocated by task 4231:
 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:3541
 kmem_cache_zalloc include/linux/slab.h:691 [inline]
 net_alloc net/core/net_namespace.c:369 [inline]
 copy_net_ns+0x152/0x580 net/core/net_namespace.c:409
 create_new_namespaces+0x425/0x880 kernel/nsproxy.c:107
 unshare_nsproxy_namespaces+0xae/0x1e0 kernel/nsproxy.c:206
 SYSC_unshare kernel/fork.c:2410 [inline]
 SyS_unshare+0x653/0xfa0 kernel/fork.c:2360
 do_syscall_64+0x282/0x940 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x26/0x9b

Freed by task 9780:
 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:3485 [inline]
 kmem_cache_free+0x83/0x2a0 mm/slab.c:3743
 net_free+0xca/0x110 net/core/net_namespace.c:385
 net_drop_ns.part.11+0x26/0x30 net/core/net_namespace.c:392
 net_drop_ns net/core/net_namespace.c:391 [inline]
 cleanup_net+0x979/0xcc0 net/core/net_namespace.c:535
 process_one_work+0xbbf/0x1af0 kernel/workqueue.c:2113
 worker_thread+0x223/0x1990 kernel/workqueue.c:2247
 kthread+0x33c/0x400 kernel/kthread.c:238
 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:429

The buggy address belongs to the object at ffff8801c80da1c0
 which belongs to the cache net_namespace of size 6720
The buggy address is located 1220 bytes inside of
 6720-byte region [ffff8801c80da1c0, ffff8801c80dbc00)
The buggy address belongs to the page:
page:ffffea0007203680 count:1 mapcount:0 mapping:ffff8801c80da1c0 index:0x0 compound_mapcount: 0
flags: 0x2fffc0000008100(slab|head)
raw: 02fffc0000008100 ffff8801c80da1c0 0000000000000000 0000000100000001
raw: ffffea0006f98520 ffffea00074e1220 ffff8801d9feae00 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801c80da580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8801c80da600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff8801c80da680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                   ^
 ffff8801c80da700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8801c80da780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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