p_mul: Detect Data PDU sequence number 0

Data PDU sequence number 0 is illegal, add an expert info for this.
Don't include this packet in SEQ/ACK analysis.

Bug: 15337
Change-Id: I476088531e8a3605393ee1dedf1e8b159dac342b
Reviewed-on: https://code.wireshark.org/review/30980
Petri-Dish: Stig Bjørlykke <stig@bjorlykke.org>
Tested-by: Petri Dish Buildbot
Reviewed-by: Anders Broman <a.broman58@gmail.com>

1 files changed, 11 insertions, 1 deletions

diff --git a/epan/dissectors/packet-p_mul.c b/epan/dissectors/packet-p_mul.c
index 8705b147d1..f82e77cccc 100644
--- a/epan/dissectors/packet-p_mul.c
+++ b/epan/dissectors/packet-p_mul.c
@@ -151,6 +151,7 @@ static gint ett_msg_fragments = -1;
 
 static expert_field ei_more_data = EI_INIT;
 static expert_field ei_checksum_bad = EI_INIT;
+static expert_field ei_illegal_seq_no = EI_INIT;
 static expert_field ei_tot_miss_seq_no = EI_INIT;
 static expert_field ei_miss_seq_no = EI_INIT;
 static expert_field ei_analysis_ack_missing = EI_INIT;
@@ -356,6 +357,11 @@ static p_mul_seq_val *register_p_mul_id (packet_info *pinfo, address *addr, guin
     return NULL;
   }
 
+  if (pdu_type == Data_PDU && seq_no == 0) {
+    /* Illegal sequence number for Data PDU */
+    return NULL;
+  }
+
   nstime_set_zero(&addr_time);
   nstime_set_zero(&prev_time);
 
@@ -864,7 +870,10 @@ static int dissect_p_mul (tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, v
   case Data_PDU:
     /* Sequence Number of PDUs */
     seq_no = tvb_get_ntohs (tvb, offset);
-    proto_tree_add_item (p_mul_tree, hf_seq_no, tvb, offset, 2, ENC_BIG_ENDIAN);
+    en = proto_tree_add_item (p_mul_tree, hf_seq_no, tvb, offset, 2, ENC_BIG_ENDIAN);
+    if (seq_no == 0) {
+      expert_add_info(pinfo, en, &ei_illegal_seq_no);
+    }
     proto_item_append_text (ti, ", Seq no: %u", seq_no);
     break;
 
@@ -1533,6 +1542,7 @@ void proto_register_p_mul (void)
       { &ei_miss_seq_range, { "p_mul.missing_seq_range.invalid", PI_UNDECODED, PI_WARN, "Invalid missing sequence range", EXPFILL }},
       { &ei_miss_seq_no, { "p_mul.missing_seq_no.invalid", PI_UNDECODED, PI_WARN, "Invalid missing seq number", EXPFILL }},
       { &ei_tot_miss_seq_no, { "p_mul.no_missing_seq_no.expert", PI_RESPONSE_CODE, PI_NOTE, "Missing seq numbers", EXPFILL }},
+      { &ei_illegal_seq_no, { "p_mul.seq_no.illegal", PI_PROTOCOL, PI_WARN, "Illegal seq number", EXPFILL }},
       { &ei_length, { "p_mul.length.invalid", PI_MALFORMED, PI_WARN, "Incorrect length field", EXPFILL }},
       { &ei_more_data, { "p_mul.more_data", PI_MALFORMED, PI_WARN, "More data in packet", EXPFILL }},
   };