Wireshark-bugs: [Wireshark-bugs] [Bug 8043] Ethernet/VLAN/MPLS/IPv4/ICMP: very very large loop
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From: bugzilla-daemon@xxxxxxxxxxxxx
Date: Thu, 06 Dec 2012 15:08:45 +0000

changed bug 8043

What Removed Added
Summary Ethernet/VLAN/MPLS/IPv4/ICMP infinite loop Ethernet/VLAN/MPLS/IPv4/ICMP: very very large loop

Comment # 8 on bug 8043 from 
In the (presumably handcrafted!) cap file ipv4.pcap (attachment #1 [details])
the layers are:

  ethernet
  vlan
  vlan
  mpls


[ repeated about 20+ times:
  ethernet
  vlan
  mpls
}

  ethernet
  ip
  icmp


The bug is somewhat interesting:
  A MPLS payload starting with a valid-looking ethernet address is
  dissected (and added to the tree) twice: once as ethernet and then again as
  pw-eth-cw (or pw-eth-nocw).

So: the effect is that the lowest-level MPLS payload is dissected (and added to
the tree) 2*N times where N is the number of MPLS layers in the frame.

In this case, about 2*22 times (4,194,304) !

So: the loop is not infinite. :)

-------

Attachments #2 & #3 are similar (many layers of MPLS) with the same issue.

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