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Modbus: do not trigger an exception before saving pkt_info structure 

Otherwise on second pass pkt_info is null, leading to a segmentation fault

Bug: 13925
Change-Id: I61cfbee894506fb6c4205c9a2ad19e6973821f23
Reviewed-on: https://code.wireshark.org/review/22833
Reviewed-by: Pascal Quantin <pascal.quantin@gmail.com>
Petri-Dish: Pascal Quantin <pascal.quantin@gmail.com>
Tested-by: Petri Dish Buildbot <buildbot-no-reply@wireshark.org>
Reviewed-by: Michael Mann <mmann78@netscape.net>
This commit is contained in:
Pascal Quantin 2017-07-28 17:59:52 +02:00 committed by Michael Mann
parent 621ff8e616
commit b16d487cbc
1 changed files with 7 additions and 3 deletions
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10
epan/dissectors/packet-mbtcp.c
View File

@ -1568,13 +1568,17 @@ dissect_modbus(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data)
if (*packet_type == QUERY_PACKET) {
/*create the modbus_request frame. It holds the request information.*/
modbus_request_info_t *frame_ptr = wmem_new(wmem_file_scope(), modbus_request_info_t);
modbus_request_info_t *frame_ptr = wmem_new0(wmem_file_scope(), modbus_request_info_t);
gint captured_length = tvb_captured_length(tvb);
/* load information into the modbus request frame */
frame_ptr->fnum = pinfo->num;
frame_ptr->function_code = function_code;
pkt_info->reg_base = frame_ptr->base_address = tvb_get_ntohs(tvb, 1);
pkt_info->num_reg = frame_ptr->num_reg = tvb_get_ntohs(tvb, 3);
if (captured_length >= 3) {
pkt_info->reg_base = frame_ptr->base_address = tvb_get_ntohs(tvb, 1);
if (captured_length >= 5)
pkt_info->num_reg = frame_ptr->num_reg = tvb_get_ntohs(tvb, 3);
}
wmem_list_prepend(modbus_conv_data->modbus_request_frame_data, frame_ptr);
}