BUG: please report to dccp@vger.kernel.org => prev = 0, last = 0 at net/dccp/ccids/lib/packet_history.c:409/tfrc_rx_hist_sample_rtt() CPU: 0 PID: 26797 Comm: syz-executor.0 Not tainted 5.7.0-rc2-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x188/0x20d lib/dump_stack.c:118 tfrc_rx_hist_sample_rtt.cold+0x57/0x6a net/dccp/ccids/lib/packet_history.c:409 ccid3_hc_rx_packet_recv+0x5cd/0xed2 net/dccp/ccids/ccid3.c:754 ccid_hc_rx_packet_recv net/dccp/ccid.h:182 [inline] dccp_deliver_input_to_ccids+0xe1/0x260 net/dccp/input.c:176 dccp_rcv_established net/dccp/input.c:374 [inline] dccp_rcv_established+0x7c/0xc0 net/dccp/input.c:364 dccp_v4_do_rcv+0x12e/0x190 net/dccp/ipv4.c:655 sk_backlog_rcv include/net/sock.h:996 [inline] __sk_receive_skb+0x323/0xc80 net/core/sock.c:519 dccp_v4_rcv+0xf8a/0x1e81 net/dccp/ipv4.c:876 ip_protocol_deliver_rcu+0x57/0x880 net/ipv4/ip_input.c:204 ip_local_deliver_finish+0x220/0x360 net/ipv4/ip_input.c:231 NF_HOOK include/linux/netfilter.h:307 [inline] NF_HOOK include/linux/netfilter.h:301 [inline] ip_local_deliver+0x1c8/0x4e0 net/ipv4/ip_input.c:252 dst_input include/net/dst.h:441 [inline] ip_rcv_finish+0x1da/0x2f0 net/ipv4/ip_input.c:428 NF_HOOK include/linux/netfilter.h:307 [inline] NF_HOOK include/linux/netfilter.h:301 [inline] ip_rcv+0xd0/0x3c0 net/ipv4/ip_input.c:539 __netif_receive_skb_one_core+0xf5/0x160 net/core/dev.c:5188 __netif_receive_skb+0x27/0x1c0 net/core/dev.c:5302 process_backlog+0x21e/0x7a0 net/core/dev.c:6134 napi_poll net/core/dev.c:6572 [inline] net_rx_action+0x4c2/0x1070 net/core/dev.c:6640 __do_softirq+0x26c/0x9f7 kernel/softirq.c:292 do_softirq_own_stack+0x2a/0x40 arch/x86/entry/entry_64.S:1082 do_softirq.part.0+0x10f/0x160 kernel/softirq.c:337 do_softirq kernel/softirq.c:329 [inline] __local_bh_enable_ip+0x20e/0x270 kernel/softirq.c:189 local_bh_enable include/linux/bottom_half.h:32 [inline] rcu_read_unlock_bh include/linux/rcupdate.h:690 [inline] ip_finish_output2+0x957/0x2610 net/ipv4/ip_output.c:229 __ip_finish_output net/ipv4/ip_output.c:306 [inline] __ip_finish_output+0x5f3/0xbd0 net/ipv4/ip_output.c:288 ip_finish_output+0x34/0x1f0 net/ipv4/ip_output.c:316 NF_HOOK_COND include/linux/netfilter.h:296 [inline] ip_output+0x1fe/0x620 net/ipv4/ip_output.c:430 dst_output include/net/dst.h:435 [inline] ip_local_out+0xaf/0x1a0 net/ipv4/ip_output.c:125 __ip_queue_xmit+0x863/0x1c20 net/ipv4/ip_output.c:530 dccp_transmit_skb+0x968/0x12d0 net/dccp/output.c:138 dccp_xmit_packet+0x1f1/0x640 net/dccp/output.c:277 dccp_write_xmit+0x16d/0x1d0 net/dccp/output.c:359 dccp_sendmsg+0xa64/0xd20 net/dccp/proto.c:812 inet_sendmsg+0x99/0xe0 net/ipv4/af_inet.c:807 sock_sendmsg_nosec net/socket.c:652 [inline] sock_sendmsg+0xcf/0x120 net/socket.c:672 __sys_sendto+0x220/0x330 net/socket.c:2000 __do_sys_sendto net/socket.c:2012 [inline] __se_sys_sendto net/socket.c:2008 [inline] __x64_sys_sendto+0xdd/0x1b0 net/socket.c:2008 do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:295 entry_SYSCALL_64_after_hwframe+0x49/0xb3 RIP: 0033:0x45c829 Code: 0d b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 db b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007f3c861c1c78 EFLAGS: 00000246 ORIG_RAX: 000000000000002c RAX: ffffffffffffffda RBX: 0000000000500f60 RCX: 000000000045c829 RDX: 0000000000000001 RSI: 0000000020000240 RDI: 0000000000000004 RBP: 000000000078bf00 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 0000000000000a0e R14: 00000000004ccc56 R15: 00007f3c861c26d4