===============================
[ INFO: suspicious RCU usage. ]
4.9.205-syzkaller #0 Not tainted
-------------------------------
include/linux/inetdevice.h:205 suspicious rcu_dereference_check() usage!

other info that might help us debug this:


rcu_scheduler_active = 2, debug_locks = 0
4 locks held by syz-executor.1/10191:
 #0:  (rcu_read_lock_bh){......}, at: [<00000000d5c08599>] ip_finish_output2+0x20b/0x1280 net/ipv4/ip_output.c:198
 #1:  (rcu_read_lock_bh){......}, at: [<000000000adec7af>] __dev_queue_xmit+0x1d4/0x1bd0 net/core/dev.c:3407
 #2:  (_xmit_TUNNEL6#2){+.-...}, at: [<0000000079ceabf5>] spin_lock include/linux/spinlock.h:302 [inline]
 #2:  (_xmit_TUNNEL6#2){+.-...}, at: [<0000000079ceabf5>] __netif_tx_lock include/linux/netdevice.h:3573 [inline]
 #2:  (_xmit_TUNNEL6#2){+.-...}, at: [<0000000079ceabf5>] __dev_queue_xmit+0x1116/0x1bd0 net/core/dev.c:3469
 #3:  (slock-AF_INET){+.-...}, at: [<00000000b8151a22>] spin_trylock include/linux/spinlock.h:312 [inline]
 #3:  (slock-AF_INET){+.-...}, at: [<00000000b8151a22>] icmp_xmit_lock net/ipv4/icmp.c:220 [inline]
 #3:  (slock-AF_INET){+.-...}, at: [<00000000b8151a22>] __icmp_send+0x48b/0x1420 net/ipv4/icmp.c:656

stack backtrace:
CPU: 1 PID: 10191 Comm: syz-executor.1 Not tainted 4.9.205-syzkaller #0
 ffff8801915c6dd8 ffffffff81b55e6b ffff8801cb2488c0 0000000000000000
 0000000000000002 00000000000000cd ffff8801a1758000 ffff8801915c6e08
 ffffffff81406997 ffff8801cb248918 ffff8801915c6f28 ffff8801a2af0000
Call Trace:
 [<0000000071193504>] __dump_stack lib/dump_stack.c:15 [inline]
 [<0000000071193504>] dump_stack+0xcb/0x130 lib/dump_stack.c:56
 [<00000000b47bde0e>] lockdep_rcu_suspicious.cold+0x10a/0x149 kernel/locking/lockdep.c:4458
 [<0000000090225468>] __in_dev_get_rcu include/linux/inetdevice.h:205 [inline]
 [<0000000090225468>] fib_compute_spec_dst+0x6c4/0xcc0 net/ipv4/fib_frontend.c:284
 [<0000000070de5d89>] __ip_options_echo+0x4be/0x13e0 net/ipv4/ip_options.c:177
 [<0000000073d45e92>] __icmp_send+0x648/0x1420 net/ipv4/icmp.c:685
 [<00000000d0496cf9>] ipv4_send_dest_unreach net/ipv4/route.c:1203 [inline]
 [<00000000d0496cf9>] ipv4_link_failure+0x460/0x850 net/ipv4/route.c:1210
 [<00000000858b9561>] dst_link_failure include/net/dst.h:490 [inline]
 [<00000000858b9561>] vti6_xmit net/ipv6/ip6_vti.c:522 [inline]
 [<00000000858b9561>] vti6_tnl_xmit+0xb08/0x17f0 net/ipv6/ip6_vti.c:561
 [<0000000049735974>] __netdev_start_xmit include/linux/netdevice.h:4072 [inline]
 [<0000000049735974>] netdev_start_xmit include/linux/netdevice.h:4081 [inline]
 [<0000000049735974>] xmit_one net/core/dev.c:2977 [inline]
 [<0000000049735974>] dev_hard_start_xmit+0x195/0x8b0 net/core/dev.c:2993
 [<0000000036c29235>] __dev_queue_xmit+0x11a3/0x1bd0 net/core/dev.c:3473
 [<00000000fe6eaed6>] dev_queue_xmit+0x18/0x20 net/core/dev.c:3506
 [<0000000037d7a89b>] neigh_direct_output+0x16/0x20 net/core/neighbour.c:1368
 [<00000000fcb5804c>] dst_neigh_output include/net/dst.h:470 [inline]
 [<00000000fcb5804c>] ip_finish_output2+0x6a2/0x1280 net/ipv4/ip_output.c:225
 [<000000006731b13e>] ip_finish_output+0x3c4/0xce0 net/ipv4/ip_output.c:313
 [<00000000101f6942>] NF_HOOK_COND include/linux/netfilter.h:246 [inline]
 [<00000000101f6942>] ip_output+0x1ec/0x5b0 net/ipv4/ip_output.c:401
 [<000000006fe542f9>] dst_output include/net/dst.h:507 [inline]
 [<000000006fe542f9>] NF_HOOK_THRESH include/linux/netfilter.h:232 [inline]
 [<000000006fe542f9>] NF_HOOK include/linux/netfilter.h:255 [inline]
 [<000000006fe542f9>] raw_send_hdrinc net/ipv4/raw.c:421 [inline]
 [<000000006fe542f9>] raw_sendmsg+0x1c5c/0x23e0 net/ipv4/raw.c:643
 [<00000000eddd1465>] inet_sendmsg+0x202/0x4d0 net/ipv4/af_inet.c:766
 [<00000000a7e45f6c>] sock_sendmsg_nosec net/socket.c:649 [inline]
 [<00000000a7e45f6c>] sock_sendmsg+0xbe/0x110 net/socket.c:659
 [<00000000b3a7bf08>] sock_write_iter+0x235/0x3d0 net/socket.c:857
 [<00000000ab807586>] new_sync_write fs/read_write.c:498 [inline]
 [<00000000ab807586>] __vfs_write+0x3c1/0x560 fs/read_write.c:511
 [<00000000c3172d96>] vfs_write+0x185/0x520 fs/read_write.c:559
 [<0000000076ca37e1>] SYSC_write fs/read_write.c:607 [inline]
 [<0000000076ca37e1>] SyS_write+0x121/0x270 fs/read_write.c:599
 [<00000000cdece64c>] do_syscall_64+0x1ad/0x5c0 arch/x86/entry/common.c:288
 [<000000007719004b>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb
tmpfs: No value for mount option 'em1'