[lwip-devel] [bug #63306] Is it possible that pcb->lastack is greater than seg->tcphdr->seqno?

[jiangheng]

URL:
  <https://savannah.nongnu.org/bugs/?63306>

                 Summary: Is it possible that pcb->lastack is greater than
seg->tcphdr->seqno?
                 Project: lwIP - A Lightweight TCP/IP stack
               Submitter: jinag12345
               Submitted: Wed 02 Nov 2022 12:35:14 PM UTC
                Category: TCP
                Severity: 3 - Normal
              Item Group: Crash Error
                  Status: None
                 Privacy: Public
             Assigned to: None
             Open/Closed: Open
         Discussion Lock: Any
         Planned Release: None
            lwIP version: 2.1.3


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Follow-up Comments:


-------------------------------------------------------
Date: Wed 02 Nov 2022 12:35:14 PM UTC By: jiangheng <jinag12345>
in tcp_output function: 
https://git.savannah.nongnu.org/cgit/lwip.git/tree/src/core/tcp_out.c#n1309

if the seg is a retransmit segment,The peer client confirms only part of the
data of the segment. The value of pcb->lastack will be greater than that of
seg->tcphdr->seqno. line 1309 will be a bug.

because segment that part of data be confirmed will be retransmited whole
segment.
https://git.savannah.nongnu.org/cgit/lwip.git/tree/src/core/tcp_in.c#n1111







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