[lwip-devel] [bug #48328] Fatal RST/ACK loop caused by commit "fixed bug #48170"

[Ambroz Bizjak]

URL:
  <http://savannah.nongnu.org/bugs/?48328>

                 Summary: Fatal RST/ACK loop caused by commit "fixed bug
#48170"
                 Project: lwIP - A Lightweight TCP/IP stack
            Submitted by: abizjak
            Submitted on: Tue 28 Jun 2016 10:25:59 AM GMT
                Category: TCP
                Severity: 3 - Normal
              Item Group: Faulty Behaviour
                  Status: None
                 Privacy: Public
             Assigned to: None
             Open/Closed: Open
         Discussion Lock: Any
         Planned Release: 
            lwIP version: git head

    _______________________________________________________

Details:

The following commit causes a fatal DOS condition in my setup when a client
closes the connection:
http://git.savannah.gnu.org/cgit/lwip.git/commit/?id=236bc194222b604f251cd86d4715cd05d9e40f94

I can trigger the issue by having a client connect to the device (TCP server)
and the device send unlimited amounts of data, then close the client
application shortly. The result is that the client machine and the device get
caught in an infinite loop, the device sending ACK and the client machine
always responding with RST.

I am absolutely positive this commit is the cause. However I am using a
significantly modified lwIP version.

Attached is a Wireshark capture of the event, and below is a text summary of
the packets. The device is 192.168.111.142.

      6 0.000663843    192.168.111.140       192.168.111.142       TCP      54
    50210 → 80 [ACK] Seq=122206028 Ack=11397555 Win=64240 Len=0
      7 0.000853303    192.168.111.142       192.168.111.140       TCP     
254    80 → 50210 [PSH, ACK] Seq=11397555 Ack=122206028 Win=3341 Len=200
      8 0.000872639    192.168.111.140       192.168.111.142       TCP      54
    50210 → 80 [ACK] Seq=122206028 Ack=11397755 Win=64240 Len=0
      9 0.001238707    192.168.111.140       192.168.111.142       TCP      54
    50210 → 80 [FIN, ACK] Seq=122206028 Ack=11397755 Win=64240 Len=0
     10 0.001277766    192.168.111.142       192.168.111.140       TCP     
2974   80 → 50210 [PSH, ACK] Seq=11397755 Ack=122206028 Win=3341 Len=2920
     11 0.001295877    192.168.111.140       192.168.111.142       TCP      54
    50210 → 80 [RST] Seq=122206028 Win=0 Len=0
     12 0.001378830    192.168.111.142       192.168.111.140       TCP     
254    80 → 50210 [PSH, ACK] Seq=11400675 Ack=122206028 Win=3341 Len=200
     13 0.001385864    192.168.111.140       192.168.111.142       TCP      54
    50210 → 80 [RST] Seq=122206028 Win=0 Len=0
     14 0.001387629    192.168.111.142       192.168.111.140       TCP      60
    80 → 50210 [ACK] Seq=11400875 Ack=122206029 Win=3340 Len=0
     15 0.001390811    192.168.111.140       192.168.111.142       TCP      54
    50210 → 80 [RST] Seq=122206029 Win=0 Len=0
     16 0.001548564    192.168.111.142       192.168.111.140       TCP      60
    [TCP Dup ACK 14#1] 80 → 50210 [ACK] Seq=11400875 Ack=122206029 Win=3340
Len=0
     17 0.001562509    192.168.111.140       192.168.111.142       TCP      54
    50210 → 80 [RST] Seq=122206029 Win=0 Len=0
     18 0.001667626    192.168.111.142       192.168.111.140       TCP      60
    [TCP Dup ACK 14#2] 80 → 50210 [ACK] Seq=11400875 Ack=122206029 Win=3340
Len=0
     19 0.001680022    192.168.111.140       192.168.111.142       TCP      54
    50210 → 80 [RST] Seq=122206029 Win=0 Len=0
     20 0.001771583    192.168.111.142       192.168.111.140       TCP      60
    [TCP Dup ACK 14#3] 80 → 50210 [ACK] Seq=11400875 Ack=122206029 Win=3340
Len=0
     21 0.001776081    192.168.111.140       192.168.111.142       TCP      54
    50210 → 80 [RST] Seq=122206029 Win=0 Len=0




    _______________________________________________________

File Attachments:


-------------------------------------------------------
Date: Tue 28 Jun 2016 10:26:00 AM GMT  Name: error.pcapng  Size: 12kB   By:
abizjak

<http://savannah.nongnu.org/bugs/download.php?file_id=37610>

    _______________________________________________________

Reply to this item at:

  <http://savannah.nongnu.org/bugs/?48328>

_______________________________________________
  Message sent via/by Savannah
  http://savannah.nongnu.org/