osmith
/
wireshark
forked from osmocom/wireshark
1
0
Fork 0
Code Pull Requests Releases Wiki Activity

tcp: Throw exception instead of ASSERT for unknown PDU length 

If a subdissector requests one more segment for a PDU of unknown length,
but we can't do reassembly for whatever reason, that's not necesarily a
dissector bug (while it could be the result of a bad heuristic, it can
happen from a checksum failing validation or reassembly preferences
disabled.)

The correct error is a FragmentBoundsError (dissector requested bytes
that it couldn't get due to not being reassembled), which is what
we would also throw if the returned PDU length were greater than the
tvb length instead of unknown. Fix #16689.
This commit is contained in:
John Thacker 2021-10-23 21:44:21 -04:00 committed by Wireshark GitLab Utility
parent c79e35d45c
commit b5989badb4
1 changed files with 10 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

11
epan/dissectors/packet-tcp.c
View File

@ -4049,7 +4049,16 @@ tcp_dissect_pdus(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree,
* Support protocols which have a variable length which cannot
* always be determined within the given fixed_len.
*/
DISSECTOR_ASSERT(proto_desegment && pinfo->can_desegment);
/*
* If another segment was requested but we can't do reassembly,
* abort and warn about the unreassembled packet.
*/
THROW_ON(!(proto_desegment && pinfo->can_desegment), FragmentBoundsError);
/*
* Tell the TCP dissector where the data for this message
* starts in the data it handed us, and that we need one
* more segment, and return.
*/
pinfo->desegment_offset = offset;
pinfo->desegment_len = DESEGMENT_ONE_MORE_SEGMENT;
return;