syzbot

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BUG: KASAN: use-after-free in inet_create+0xfdb/0x1070 net/ipv4/af_inet.c:340
Read of size 4 at addr ffff8801a1800804 by task kworker/u4:5/6496

CPU: 0 PID: 6496 Comm: kworker/u4:5 Not tainted 4.18.0-rc7+ #167
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:77 [inline]
 dump_stack+0x1c9/0x2b4 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
IPVS: ftp: loaded support on port[0] = 21
 __asan_report_load4_noabort+0x14/0x20 mm/kasan/report.c:432
 inet_create+0xfdb/0x1070 net/ipv4/af_inet.c:340
 __sock_create+0x53c/0x940 net/socket.c:1294
 sock_create_kern+0x3b/0x50 net/socket.c:1340
 rds_tcp_conn_path_connect+0x313/0xe80 net/rds/tcp_connect.c:114
 rds_connect_worker+0x1aa/0x2d0 net/rds/threads.c:175
 process_one_work+0xc73/0x1ba0 kernel/workqueue.c:2153
 worker_thread+0x189/0x13c0 kernel/workqueue.c:2296
 kthread+0x345/0x410 kernel/kthread.c:246
 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:412

Allocated by task 4365:
 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
 kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:490
 kmem_cache_alloc+0x12e/0x760 mm/slab.c:3554
 kmem_cache_zalloc include/linux/slab.h:697 [inline]
 net_alloc net/core/net_namespace.c:384 [inline]
 copy_net_ns+0x15b/0x4d0 net/core/net_namespace.c:424
 create_new_namespaces+0x6ad/0x900 kernel/nsproxy.c:107
 unshare_nsproxy_namespaces+0xc3/0x1f0 kernel/nsproxy.c:206
 ksys_unshare+0x723/0xfb0 kernel/fork.c:2442
 __do_sys_unshare kernel/fork.c:2510 [inline]
 __se_sys_unshare kernel/fork.c:2508 [inline]
 __x64_sys_unshare+0x31/0x40 kernel/fork.c:2508
 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 67:
 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]
 kmem_cache_free+0x86/0x2d0 mm/slab.c:3756
 net_free net/core/net_namespace.c:400 [inline]
 net_drop_ns.part.15+0x129/0x150 net/core/net_namespace.c:407
 net_drop_ns net/core/net_namespace.c:406 [inline]
 cleanup_net+0x6bb/0xb50 net/core/net_namespace.c:569
 process_one_work+0xc73/0x1ba0 kernel/workqueue.c:2153
 worker_thread+0x189/0x13c0 kernel/workqueue.c:2296
 kthread+0x345/0x410 kernel/kthread.c:246
 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:412

The buggy address belongs to the object at ffff8801a1800100
 which belongs to the cache net_namespace of size 8576
The buggy address is located 1796 bytes inside of
 8576-byte region [ffff8801a1800100, ffff8801a1802280)
The buggy address belongs to the page:
page:ffffea0006860000 count:1 mapcount:0 mapping:ffff8801d9fe7e40 index:0x0 compound_mapcount: 0
flags: 0x2fffc0000008100(slab|head)
raw: 02fffc0000008100 ffffea000689af08 ffffea0006840a08 ffff8801d9fe7e40
raw: 0000000000000000 ffff8801a1800100 0000000100000001 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801a1800700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8801a1800780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff8801a1800800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                   ^
 ffff8801a1800880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8801a1800900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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