=============================
WARNING: suspicious RCU usage
4.14.232-syzkaller #0 Not tainted
-----------------------------
net/ipv4/tcp_ipv4.c:918 suspicious rcu_dereference_check() usage!

other info that might help us debug this:


rcu_scheduler_active = 2, debug_locks = 1
4 locks held by kworker/u4:0/5:
 #0:  ("%s""netns"){+.+.}, at: [<ffffffff813639b0>] process_one_work+0x6b0/0x14a0 kernel/workqueue.c:2087
 #1:  (net_cleanup_work){+.+.}, at: [<ffffffff813639e6>] process_one_work+0x6e6/0x14a0 kernel/workqueue.c:2091
 #2:  (net_mutex){+.+.}, at: [<ffffffff85c0eb70>] cleanup_net+0x110/0x840 net/core/net_namespace.c:450
 #3:  (rtnl_mutex){+.+.}, at: [<ffffffff85c444de>] netdev_run_todo+0x20e/0xad0 net/core/dev.c:7926

stack backtrace:
CPU: 0 PID: 5 Comm: kworker/u4:0 Not tainted 4.14.232-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+0x1b2/0x281 lib/dump_stack.c:58
 tcp_md5_do_lookup+0x3b4/0x510 net/ipv4/tcp_ipv4.c:918
 tcp_established_options+0x94/0x410 net/ipv4/tcp_output.c:690
 __tcp_transmit_skb+0x286/0x2cb0 net/ipv4/tcp_output.c:1032
 tcp_transmit_skb net/ipv4/tcp_output.c:1149 [inline]
 tcp_send_active_reset+0x40b/0x5c0 net/ipv4/tcp_output.c:3159
 tcp_disconnect+0x159/0x1890 net/ipv4/tcp.c:2341
 rds_tcp_conn_paths_destroy net/rds/tcp.c:515 [inline]
 rds_tcp_kill_sock net/rds/tcp.c:544 [inline]
 rds_tcp_dev_event+0x73f/0xa30 net/rds/tcp.c:573
 notifier_call_chain+0x108/0x1a0 kernel/notifier.c:93
 call_netdevice_notifiers_info net/core/dev.c:1667 [inline]
 call_netdevice_notifiers net/core/dev.c:1683 [inline]
 netdev_run_todo+0x242/0xad0 net/core/dev.c:7927
 default_device_exit_batch+0x2e2/0x380 net/core/dev.c:8747
 ops_exit_list+0xf9/0x150 net/core/net_namespace.c:145
 cleanup_net+0x3b3/0x840 net/core/net_namespace.c:484
 process_one_work+0x793/0x14a0 kernel/workqueue.c:2116
 worker_thread+0x5cc/0xff0 kernel/workqueue.c:2250
 kthread+0x30d/0x420 kernel/kthread.c:232
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404

=============================
WARNING: suspicious RCU usage
4.14.232-syzkaller #0 Not tainted
-----------------------------
include/net/sock.h:1800 suspicious rcu_dereference_protected() usage!

other info that might help us debug this:


rcu_scheduler_active = 2, debug_locks = 1
4 locks held by kworker/u4:0/5:
 #0:  ("%s""netns"){+.+.}, at: [<ffffffff813639b0>] process_one_work+0x6b0/0x14a0 kernel/workqueue.c:2087
 #1:  (net_cleanup_work){+.+.}, at: [<ffffffff813639e6>] process_one_work+0x6e6/0x14a0 kernel/workqueue.c:2091
 #2:  (net_mutex){+.+.}, at: [<ffffffff85c0eb70>] cleanup_net+0x110/0x840 net/core/net_namespace.c:450
 #3:  (rtnl_mutex){+.+.}, at: [<ffffffff85c444de>] netdev_run_todo+0x20e/0xad0 net/core/dev.c:7926

stack backtrace:
CPU: 0 PID: 5 Comm: kworker/u4:0 Not tainted 4.14.232-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+0x1b2/0x281 lib/dump_stack.c:58
 __sk_dst_set include/net/sock.h:1800 [inline]
 __sk_dst_reset include/net/sock.h:1820 [inline]
 tcp_disconnect+0x1412/0x1890 net/ipv4/tcp.c:2383
 rds_tcp_conn_paths_destroy net/rds/tcp.c:515 [inline]
 rds_tcp_kill_sock net/rds/tcp.c:544 [inline]
 rds_tcp_dev_event+0x73f/0xa30 net/rds/tcp.c:573
 notifier_call_chain+0x108/0x1a0 kernel/notifier.c:93
 call_netdevice_notifiers_info net/core/dev.c:1667 [inline]
 call_netdevice_notifiers net/core/dev.c:1683 [inline]
 netdev_run_todo+0x242/0xad0 net/core/dev.c:7927
 default_device_exit_batch+0x2e2/0x380 net/core/dev.c:8747
 ops_exit_list+0xf9/0x150 net/core/net_namespace.c:145
 cleanup_net+0x3b3/0x840 net/core/net_namespace.c:484
 process_one_work+0x793/0x14a0 kernel/workqueue.c:2116
 worker_thread+0x5cc/0xff0 kernel/workqueue.c:2250
 kthread+0x30d/0x420 kernel/kthread.c:232
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404