Hi, I've got the following error report while fuzzing the kernel with syzkaller.
On commit a71c9a1c779f2499fb2afc0553e543f18aff6edf (4.11-rc5). I'm able to reproduce it by executing the attached syzkaller prog, but there's no simple C reproducer. My .config is attached. BUG: please report to d...@vger.kernel.org => prev = 0, last = 0 at net/dccp/ccids/lib/packet_history.c:427/tfrc_rx_hist_sample_rtt() CPU: 1 PID: 4049 Comm: syz-executor Not tainted 4.11.0-rc5+ #199 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 Call Trace: <IRQ> __dump_stack lib/dump_stack.c:16 dump_stack+0x292/0x398 lib/dump_stack.c:52 tfrc_rx_hist_sample_rtt+0x407/0x4d0 net/dccp/ccids/lib/packet_history.c:424 ccid3_hc_rx_packet_recv+0x6a3/0xfb0 net/dccp/ccids/ccid3.c:764 ccid_hc_rx_packet_recv net/dccp/ccid.h:185 dccp_deliver_input_to_ccids+0xd9/0x250 net/dccp/input.c:180 dccp_rcv_established+0x88/0xb0 net/dccp/input.c:378 dccp_v6_do_rcv+0x2af/0x350 net/dccp/ipv6.c:600 sk_backlog_rcv ./include/net/sock.h:898 __sk_receive_skb+0x368/0xcb0 net/core/sock.c:469 dccp_v6_rcv+0xba2/0x1cf0 net/dccp/ipv6.c:744 ip6_input_finish+0x468/0x17b0 net/ipv6/ip6_input.c:279 NF_HOOK ./include/linux/netfilter.h:257 ip6_input+0xdb/0x590 net/ipv6/ip6_input.c:322 dst_input ./include/net/dst.h:492 ip6_rcv_finish+0x289/0x890 net/ipv6/ip6_input.c:69 NF_HOOK ./include/linux/netfilter.h:257 ipv6_rcv+0x12f1/0x23a0 net/ipv6/ip6_input.c:203 __netif_receive_skb_core+0x1ad1/0x3400 net/core/dev.c:4207 __netif_receive_skb+0x2a/0x170 net/core/dev.c:4245 process_backlog+0xe5/0x6c0 net/core/dev.c:4865 napi_poll net/core/dev.c:5267 net_rx_action+0xe70/0x1900 net/core/dev.c:5332 __do_softirq+0x2fb/0xb7d kernel/softirq.c:284 do_softirq_own_stack+0x1c/0x30 arch/x86/entry/entry_64.S:902 </IRQ> do_softirq.part.17+0x1e8/0x230 kernel/softirq.c:328 do_softirq kernel/softirq.c:176 __local_bh_enable_ip+0x1f2/0x200 kernel/softirq.c:181 local_bh_enable ./include/linux/bottom_half.h:31 rcu_read_unlock_bh ./include/linux/rcupdate.h:931 ip6_finish_output2+0xc4e/0x2560 net/ipv6/ip6_output.c:124 ip6_finish_output+0x302/0x960 net/ipv6/ip6_output.c:149 NF_HOOK_COND ./include/linux/netfilter.h:246 ip6_output+0x1cb/0x8d0 net/ipv6/ip6_output.c:163 ip6_xmit+0xd38/0x2210 ./include/net/dst.h:486 inet6_csk_xmit+0x331/0x610 net/ipv6/inet6_connection_sock.c:139 dccp_transmit_skb+0xb09/0x1120 net/dccp/output.c:142 dccp_xmit_packet+0x215/0x760 net/dccp/output.c:281 dccp_write_xmit+0x168/0x1d0 net/dccp/output.c:363 dccp_sendmsg+0x79c/0xb10 net/dccp/proto.c:796 inet_sendmsg+0x164/0x5b0 net/ipv4/af_inet.c:762 sock_sendmsg_nosec net/socket.c:633 sock_sendmsg+0xca/0x110 net/socket.c:643 SYSC_sendto+0x660/0x810 net/socket.c:1696 SyS_sendto+0x40/0x50 net/socket.c:1664 entry_SYSCALL_64_fastpath+0x1f/0xc2 arch/x86/entry/entry_64.S:204 RIP: 0033:0x4458d9 RSP: 002b:00007f4a98d8ab58 EFLAGS: 00000282 ORIG_RAX: 000000000000002c RAX: ffffffffffffffda RBX: 0000000000000015 RCX: 00000000004458d9 RDX: 000000000000007a RSI: 00000000203c4000 RDI: 0000000000000015 RBP: 00000000006e2fa0 R08: 0000000020e6f000 R09: 000000000000000a R10: 0000000000004000 R11: 0000000000000282 R12: 0000000000708150 R13: 0000000000000000 R14: 00007f4a98d8b9c0 R15: 00007f4a98d8b700 dccp_close: ABORT with 1 bytes unread
.config
Description: Binary data
dccp-history-bug-log
Description: Binary data
