syzbot

TCP: request_sock_TCPv6: Possible SYN flooding on port 20002. Sending cookies.  Check SNMP counters.
TCP: request_sock_TCPv6: Possible SYN flooding on port 20002. Sending cookies.  Check SNMP counters.
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BUG: KASAN: use-after-free in rds_tcp_kill_sock net/rds/tcp.c:531 [inline]
BUG: KASAN: use-after-free in rds_tcp_dev_event+0x8ef/0xa10 net/rds/tcp.c:573
Read of size 8 at addr ffff88805fc50c00 by task kworker/u4:1/8157

CPU: 1 PID: 8157 Comm: kworker/u4:1 Not tainted 4.14.184-syzkaller #0
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:17 [inline]
 dump_stack+0x1b2/0x283 lib/dump_stack.c:58
 print_address_description.cold+0x54/0x1dc mm/kasan/report.c:252
 kasan_report_error mm/kasan/report.c:351 [inline]
 kasan_report mm/kasan/report.c:409 [inline]
 kasan_report.cold+0xa9/0x2b9 mm/kasan/report.c:393
 rds_tcp_kill_sock net/rds/tcp.c:531 [inline]
 rds_tcp_dev_event+0x8ef/0xa10 net/rds/tcp.c:573
 notifier_call_chain+0x107/0x1a0 kernel/notifier.c:93
 call_netdevice_notifiers net/core/dev.c:1687 [inline]
 netdev_run_todo+0x1f6/0x710 net/core/dev.c:7923
 default_device_exit_batch+0x2e7/0x380 net/core/dev.c:8743
 ops_exit_list.isra.0+0xef/0x140 net/core/net_namespace.c:145
 cleanup_net+0x3bb/0x820 net/core/net_namespace.c:484
 process_one_work+0x7c0/0x14c0 kernel/workqueue.c:2116
 worker_thread+0x5d7/0x1080 kernel/workqueue.c:2250
 kthread+0x30d/0x420 kernel/kthread.c:232
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404

Allocated by task 26248:
 save_stack mm/kasan/kasan.c:447 [inline]
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_kmalloc.part.0+0x4f/0xd0 mm/kasan/kasan.c:551
 kmem_cache_alloc+0x124/0x3c0 mm/slab.c:3552
 getname_flags+0xc8/0x550 fs/namei.c:138
 do_sys_open+0x202/0x3e0 fs/open.c:1075
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb

Freed by task 26248:
 save_stack mm/kasan/kasan.c:447 [inline]
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_slab_free+0xaf/0x190 mm/kasan/kasan.c:524
 __cache_free mm/slab.c:3496 [inline]
 kmem_cache_free+0x7c/0x2b0 mm/slab.c:3758
 putname+0xcd/0x110 fs/namei.c:259
 do_sys_open+0x233/0x3e0 fs/open.c:1090
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb

The buggy address belongs to the object at ffff88805fc50940
 which belongs to the cache names_cache of size 4096
The buggy address is located 704 bytes inside of
 4096-byte region [ffff88805fc50940, ffff88805fc51940)
The buggy address belongs to the page:
page:ffffea00017f1400 count:1 mapcount:0 mapping:ffff88805fc50940 index:0x0 compound_mapcount: 0
flags: 0xfffe0000008100(slab|head)
raw: 00fffe0000008100 ffff88805fc50940 0000000000000000 0000000100000001
raw: ffffea00029053a0 ffffea00017f14a0 ffff8880aa9dacc0 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88805fc50b00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88805fc50b80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88805fc50c00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                   ^
 ffff88805fc50c80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88805fc50d00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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