syzbot

=============================
WARNING: suspicious RCU usage
4.14.300-syzkaller #0 Not tainted
-----------------------------
net/sched/act_sample.c:95 suspicious rcu_dereference_protected() usage!

other info that might help us debug this:


rcu_scheduler_active = 2, debug_locks = 1
1 lock held by syz-executor156/7973:
 #0:  (rtnl_mutex){+.+.}, at: [<ffffffff85c8aabd>] rtnl_lock net/core/rtnetlink.c:72 [inline]
 #0:  (rtnl_mutex){+.+.}, at: [<ffffffff85c8aabd>] rtnetlink_rcv_msg+0x31d/0xb10 net/core/rtnetlink.c:4317

stack backtrace:
CPU: 0 PID: 7973 Comm: syz-executor156 Not tainted 4.14.300-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x1b2/0x281 lib/dump_stack.c:58
 tcf_sample_init+0x71c/0x8c0 net/sched/act_sample.c:95
 tcf_action_init_1+0x51a/0x9e0 net/sched/act_api.c:691
 tcf_action_init+0x26d/0x400 net/sched/act_api.c:760
 tcf_action_add net/sched/act_api.c:1088 [inline]
 tc_ctl_action+0x2e3/0x510 net/sched/act_api.c:1140
 rtnetlink_rcv_msg+0x3be/0xb10 net/core/rtnetlink.c:4322
 netlink_rcv_skb+0x125/0x390 net/netlink/af_netlink.c:2454
 netlink_unicast_kernel net/netlink/af_netlink.c:1296 [inline]
 netlink_unicast+0x437/0x610 net/netlink/af_netlink.c:1322
 netlink_sendmsg+0x648/0xbc0 net/netlink/af_netlink.c:1893
 sock_sendmsg_nosec net/socket.c:646 [inline]
 sock_sendmsg+0xb5/0x100 net/socket.c:656
 ___sys_sendmsg+0x6c8/0x800 net/socket.c:2062
 __sys_sendmsg+0xa3/0x120 net/socket.c:2096
 SYSC_sendmsg net/socket.c:2107 [inline]
 SyS_sendmsg+0x27/0x40 net/socket.c:2103
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_aft