BUG: please report to [email protected] => prev = 10, last = 10 at net/dccp/ccids/lib/packet_hist

Hello,

syzbot found the following crash on:

HEAD commit:    6531e115b7ab Merge branch 'akpm' (patches from Andrew)
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?xb0bd5d400000
kernel config:  https://syzkaller.appspot.com/x/.config?xÈ970c89a0efbb23
dashboard link: https://syzkaller.appspot.com/bug?extid<8a843d9de82272915b
compiler:       gcc (GCC) 8.0.1 20180413 (experimental)

Unfortunately, I don't have any reproducer for this crash yet.

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: [email protected]

bond0: enslaved VLAN challenged slave lo. Adding VLANs will be blocked as  
long as lo is part of bond bond0
bond0: lo is up - this may be due to an out of date ifenslave
A link change request failed with some changes committed already. Interface  
lo may have been left with an inconsistent configuration, please check.
BUG: please report to [email protected] => prev = 10, last = 10 at  
net/dccp/ccids/lib/packet_history.c:425/tfrc_rx_hist_sample_rtt()
CPU: 0 PID: 9 Comm: ksoftirqd/0 Not tainted 4.20.0-rc6+ #374
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+0x244/0x39d lib/dump_stack.c:113
  tfrc_rx_hist_sample_rtt.cold.3+0x54/0x5c  
net/dccp/ccids/lib/packet_history.c:422
  ccid3_hc_rx_packet_recv+0x5c4/0xeb0 net/dccp/ccids/ccid3.c:767
  ccid_hc_rx_packet_recv net/dccp/ccid.h:185 [inline]
  dccp_deliver_input_to_ccids+0xf0/0x280 net/dccp/input.c:180
  dccp_rcv_established+0x87/0xb0 net/dccp/input.c:378
  dccp_v4_do_rcv+0x153/0x180 net/dccp/ipv4.c:656
  sk_backlog_rcv include/net/sock.h:932 [inline]
  __sk_receive_skb+0x3e5/0xec0 net/core/sock.c:473
  dccp_v4_rcv+0x10f9/0x1f58 net/dccp/ipv4.c:877
  ip_local_deliver_finish+0x2e9/0xda0 net/ipv4/ip_input.c:215
  NF_HOOK include/linux/netfilter.h:289 [inline]
  ip_local_deliver+0x1e9/0x750 net/ipv4/ip_input.c:256
  dst_input include/net/dst.h:450 [inline]
  ip_rcv_finish+0x1f9/0x300 net/ipv4/ip_input.c:415
  NF_HOOK include/linux/netfilter.h:289 [inline]
  ip_rcv+0xed/0x600 net/ipv4/ip_input.c:524
  __netif_receive_skb_one_core+0x14d/0x200 net/core/dev.c:4946
  __netif_receive_skb+0x2c/0x1e0 net/core/dev.c:5056
  process_backlog+0x24e/0x7a0 net/core/dev.c:5864
  napi_poll net/core/dev.c:6287 [inline]
  net_rx_action+0x7fa/0x19b0 net/core/dev.c:6353
  __do_softirq+0x308/0xb7e kernel/softirq.c:292
  run_ksoftirqd+0x5e/0x100 kernel/softirq.c:654
  smpboot_thread_fn+0x68b/0xa00 kernel/smpboot.c:164
  kthread+0x35a/0x440 kernel/kthread.c:246
  ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:352
IPv6: ADDRCONF(NETDEV_CHANGE): vcan0: link becomes ready
IPVS: ftp: loaded support on port[0] = 21
dccp_close: ABORT with 36864 bytes unread
bond0: enslaved VLAN challenged slave lo. Adding VLANs will be blocked as  
long as lo is part of bond bond0
bond0: lo is up - this may be due to an out of date ifenslave
A link change request failed with some changes committed already. Interface  
lo may have been left with an inconsistent configuration, please check.
IPv6: ADDRCONF(NETDEV_CHANGE): vcan0: link becomes ready
IPv6: ADDRCONF(NETDEV_CHANGE): vcan0: link becomes ready
bond0: enslaved VLAN challenged slave lo. Adding VLANs will be blocked as  
long as lo is part of bond bond0
bond0: lo is up - this may be due to an out of date ifenslave
A link change request failed with some changes committed already. Interface  
lo may have been left with an inconsistent configuration, please check.
IPVS: ftp: loaded support on port[0] = 21
bond0: enslaved VLAN challenged slave lo. Adding VLANs will be blocked as  
long as lo is part of bond bond0
bond0: lo is up - this may be due to an out of date ifenslave
A link change request failed with some changes committed already. Interface  
lo may have been left with an inconsistent configuration, please check.
IPv6: ADDRCONF(NETDEV_CHANGE): vcan0: link becomes ready
IPVS: ftp: loaded support on port[0] = 21
IPv6: ADDRCONF(NETDEV_CHANGE): vcan0: link becomes ready
bond0: enslaved VLAN challenged slave lo. Adding VLANs will be blocked as  
long as lo is part of bond bond0
bond0: lo is up - this may be due to an out of date ifenslave
A link change request failed with some changes committed already. Interface  
lo may have been left with an inconsistent configuration, please check.
IPv6: ADDRCONF(NETDEV_CHANGE): vcan0: link becomes ready
bond0: enslaved VLAN challenged slave lo. Adding VLANs will be blocked as  
long as lo is part of bond bond0
bond0: lo is up - this may be due to an out of date ifenslave
IPVS: ftp: loaded support on port[0] = 21
A link change request failed with some changes committed already. Interface  
lo may have been left with an inconsistent configuration, please check.
IPv6: ADDRCONF(NETDEV_CHANGE): vcan0: link becomes ready
bond0: enslaved VLAN challenged slave lo. Adding VLANs will be blocked as  
long as lo is part of bond bond0
bond0: lo is up - this may be due to an out of date ifenslave
A link change request failed with some changes committed already. Interface  
lo may have been left with an inconsistent configuration, please check.
IPVS: ftp: loaded support on port[0] = 21
IPv6: ADDRCONF(NETDEV_CHANGE): vcan0: link becomes ready
bond0: enslaved VLAN challenged slave lo. Adding VLANs will be blocked as  
long as lo is part of bond bond0
bond0: lo is up - this may be due to an out of date ifenslave
IPVS: ftp: loaded support on port[0] = 21
A link change request failed with some changes committed already. Interface  
lo may have been left with an inconsistent configuration, please check.
IPv6: ADDRCONF(NETDEV_CHANGE): vcan0: link becomes ready
IPVS: ftp: loaded support on port[0] = 21
IPv6: ADDRCONF(NETDEV_CHANGE): vcan0: link becomes ready
bond0: enslaved VLAN challenged slave lo. Adding VLANs will be blocked as  
long as lo is part of bond bond0
bond0: lo is up - this may be due to an out of date ifenslave
IPVS: ftp: loaded support on port[0] = 21
A link change request failed with some changes committed already. Interface  
lo may have been left with an inconsistent configuration, please check.
IPv6: ADDRCONF(NETDEV_CHANGE): vcan0: link becomes ready
IPVS: ftp: loaded support on port[0] = 21
IPv6: ADDRCONF(NETDEV_CHANGE): vcan0: link becomes ready
bond0: enslaved VLAN challenged slave lo. Adding VLANs will be blocked as  
long as lo is part of bond bond0
bond0: lo is up - this may be due to an out of date ifenslave
A link change request failed with some changes committed already. Interface  
lo may have been left with an inconsistent configuration, please check.
IPVS: ftp: loaded support on port[0] = 21
IPv6: ADDRCONF(NETDEV_CHANGE): vcan0: link becomes ready
bond0: enslaved VLAN challenged slave lo. Adding VLANs will be blocked as  
long as lo is part of bond bond0
bond0: lo is up - this may be due to an out of date ifenslave
A link change request failed with some changes committed already. Interface  
lo may have been left with an inconsistent configuration, please check.
IPv6: ADDRCONF(NETDEV_CHANGE): vcan0: link becomes ready
IPv6: ADDRCONF(NETDEV_CHANGE): vcan0: link becomes ready
bond0: enslaved VLAN challenged slave lo. Adding VLANs will be blocked as  
long as lo is part of bond bond0
bond0: lo is up - this may be due to an out of date ifenslave
A link change request failed with some changes committed already. Interface  
lo may have been left with an inconsistent configuration, please check.


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