[lwip-devel] [bug #45322] ICMP echo reply checksum wrong on NULL Bytes payload

[TabascoEye]

URL:
  <http://savannah.nongnu.org/bugs/?45322>

                 Summary: ICMP echo reply checksum wrong on NULL Bytes payload
                 Project: lwIP - A Lightweight TCP/IP stack
            Submitted by: tabascoeye
            Submitted on: Mo 15 Jun 2015 09:23:12 GMT
                Category: IPv4
                Severity: 3 - Normal
              Item Group: Faulty Behaviour
                  Status: None
                 Privacy: Public
             Assigned to: None
             Open/Closed: Open
         Discussion Lock: Any
         Planned Release: 
            lwIP version: 1.4.1

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Details:

When a client sends an ICMP echo request with ID 0, Sequence 0 and either no
data or any amount of 0x00 Bytes as data, the checksum in the reply by LWIP is
wrong (off-by-one).

Expected checksum is 0xffff in that case, observed is 0x0000.
So the client does not see that reply as valid and determines the LWIP device
as unreachable.

Attached patch fixes the off-by-one error when checksum should be 0xffff



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File Attachments:


-------------------------------------------------------
Date: Mo 15 Jun 2015 09:23:12 GMT  Name: ping_reply_to_0_bytes_payload.diff 
Size: 553B   By: tabascoeye

<http://savannah.nongnu.org/bugs/download.php?file_id=34223>

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Reply to this item at:

  <http://savannah.nongnu.org/bugs/?45322>

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