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ptp: prevent divide by zero. 

Check for valid values before use.

Fix: #18635.
This commit is contained in:
Dario Lombardo 2022-11-16 22:25:42 +01:00
parent fc28bb0502
commit baaf60cb34
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GPG Key ID: A45A48B6693FB191
1 changed files with 36 additions and 12 deletions
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48
epan/dissectors/packet-ptp.c
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@ -1801,6 +1801,7 @@ static expert_field ei_ptp_v2_pdresp_no_pdreq = EI_INIT;
static expert_field ei_ptp_v2_pdresp_no_pdfup = EI_INIT;
static expert_field ei_ptp_v2_pdresp_twostep = EI_INIT;
static expert_field ei_ptp_v2_pdfup_no_pdresp = EI_INIT;
static expert_field ei_ptp_v2_period_invalid = EI_INIT;
/* END Definitions and fields for PTPv2 dissection. */
@ -2924,15 +2925,19 @@ dissect_ptp_v2(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, gboolean ptp
nstime_delta(&delta_capture_ts, &(frame_info->sync.sync_ts), &(frame_info->prev->sync.sync_ts));
frame_info->sync.syncInterval = nstime_to_sec(&delta_capture_ts);
frame_info->sync.syncInterval_valid = true;
if (frame_info->sync.syncInterval > 0)
frame_info->sync.syncInterval_valid = true;
if (PTP_FRAME_INFO_SYNC_COMPLETE(frame_info->prev) && frame_info->sync.calculated_timestamp_valid && frame_info->prev->sync.calculated_timestamp_valid) {
nstime_t delta_sync_ts;
nstime_delta(&delta_sync_ts, &(frame_info->sync.calculated_timestamp), &(frame_info->prev->sync.calculated_timestamp));
frame_info->sync.syncRateRatio = nstime_to_sec(&delta_sync_ts) / nstime_to_sec(&delta_capture_ts);
frame_info->sync.syncRateRatio_valid = true;
frame_info->sync.syncRateRatio_ppm = (gint32)((1.0 - frame_info->sync.syncRateRatio) * 1000 * 1000);
if (frame_info->sync.syncInterval_valid) {
frame_info->sync.syncRateRatio = nstime_to_sec(&delta_sync_ts) / nstime_to_sec(&delta_capture_ts);
frame_info->sync.syncRateRatio_valid = true;
frame_info->sync.syncRateRatio_ppm =
(gint32)((1.0 - frame_info->sync.syncRateRatio) * 1000 * 1000);
}
}
}
}
@ -2942,7 +2947,8 @@ dissect_ptp_v2(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, gboolean ptp
nstime_delta(&t4_delta, &frame_info->pdelay.pdelay_res_ts, &frame_info->prev->pdelay.pdelay_res_ts);
frame_info->pdelay.pdelayInterval = nstime_to_sec(&t4_delta);
frame_info->pdelay.pdelayInterval_valid = true;
if (frame_info->pdelay.pdelayInterval > 0)
frame_info->pdelay.pdelayInterval_valid = true;
if (PTP_FRAME_INFO_PDELAY_COMPLETE(frame_info) && PTP_FRAME_INFO_PDELAY_COMPLETE(frame_info->prev)) {
/* lets calculate rate t3_delta / t4_delta */
@ -2951,9 +2957,12 @@ dissect_ptp_v2(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, gboolean ptp
nstime_t t3_prev = NSTIME_INIT_SECS_NSECS(frame_info->prev->pdelay.pdelay_res_send_ts_s, frame_info->prev->pdelay.pdelay_res_send_ts_ns);
nstime_delta(&t3_delta, &t3_curr, &t3_prev);
frame_info->pdelay.neighborRateRatio = nstime_to_sec(&t3_delta) / nstime_to_sec(&t4_delta);
frame_info->pdelay.neighborRateRatio_valid = true;
frame_info->pdelay.neighborRateRatio_ppm = (gint32)((1.0 - frame_info->pdelay.neighborRateRatio) * 1000 * 1000);
if (frame_info->pdelay.pdelayInterval_valid) {
frame_info->pdelay.neighborRateRatio = nstime_to_sec(&t3_delta) / nstime_to_sec(&t4_delta);
frame_info->pdelay.neighborRateRatio_valid = true;
frame_info->pdelay.neighborRateRatio_ppm =
(gint32)((1.0 - frame_info->pdelay.neighborRateRatio) * 1000 * 1000);
}
}
}
@ -4042,7 +4051,6 @@ dissect_ptp_v2(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, gboolean ptp
/* 16.1.4.1.4 logInterMessagePeriod */
log_inter_message_period = tvb_get_guint8(tvb, tlv_offset + PTP_V2_SIG_TLV_LOG_INTER_MESSAGE_PERIOD_OFFSET);
period = pow(2, log_inter_message_period);
rate = 1/period;
ptp_tlv_period = proto_tree_add_item(ptp_tlv_tree, hf_ptp_v2_sig_tlv_logInterMessagePeriod, tvb,
tlv_offset + PTP_V2_SIG_TLV_LOG_INTER_MESSAGE_PERIOD_OFFSET, PTP_V2_SIG_TLV_LOG_INTER_MESSAGE_PERIOD_LEN, ENC_BIG_ENDIAN);
@ -4052,8 +4060,16 @@ dissect_ptp_v2(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, gboolean ptp
proto_tree_add_int_format_value(ptp_tlv_period_tree, hf_ptp_v2_sig_tlv_logInterMessagePeriod_period, tvb,
tlv_offset + PTP_V2_SIG_TLV_LOG_INTER_MESSAGE_PERIOD_OFFSET, PTP_V2_SIG_TLV_LOG_INTER_MESSAGE_PERIOD_LEN, log_inter_message_period, "every %lg seconds", period);
proto_tree_add_int_format_value(ptp_tlv_period_tree, hf_ptp_v2_sig_tlv_logInterMessagePeriod_rate, tvb,
if (period > 0) {
rate = 1 / period;
proto_tree_add_int_format_value(ptp_tlv_period_tree, hf_ptp_v2_sig_tlv_logInterMessagePeriod_rate, tvb,
tlv_offset + PTP_V2_SIG_TLV_LOG_INTER_MESSAGE_PERIOD_OFFSET, PTP_V2_SIG_TLV_LOG_INTER_MESSAGE_PERIOD_LEN, log_inter_message_period, "%lg packets/sec", rate);
} else {
proto_tree_add_expert_format(ptp_tlv_period_tree, pinfo, &ei_ptp_v2_period_invalid,
tvb, tlv_offset + PTP_V2_SIG_TLV_LOG_INTER_MESSAGE_PERIOD_OFFSET,
PTP_V2_SIG_TLV_LOG_INTER_MESSAGE_PERIOD_LEN,
"Invalid InterMessagePeriod: %lg", period);
}
/* 16.1.4.1.5 durationField */
proto_tree_add_item(ptp_tlv_tree, hf_ptp_v2_sig_tlv_durationField, tvb,
@ -4071,7 +4087,6 @@ dissect_ptp_v2(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, gboolean ptp
/* 16.1.4.2.4 logInterMessagePeriod */
log_inter_message_period = tvb_get_guint8(tvb, tlv_offset + PTP_V2_SIG_TLV_LOG_INTER_MESSAGE_PERIOD_OFFSET);
period = pow(2, log_inter_message_period);
rate = 1/period;
ptp_tlv_period = proto_tree_add_item(ptp_tlv_tree, hf_ptp_v2_sig_tlv_logInterMessagePeriod, tvb,
tlv_offset + PTP_V2_SIG_TLV_LOG_INTER_MESSAGE_PERIOD_OFFSET, PTP_V2_SIG_TLV_LOG_INTER_MESSAGE_PERIOD_LEN, ENC_BIG_ENDIAN);
@ -4081,8 +4096,16 @@ dissect_ptp_v2(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, gboolean ptp
proto_tree_add_int_format_value(ptp_tlv_period_tree, hf_ptp_v2_sig_tlv_logInterMessagePeriod_period, tvb,
tlv_offset + PTP_V2_SIG_TLV_LOG_INTER_MESSAGE_PERIOD_OFFSET, PTP_V2_SIG_TLV_LOG_INTER_MESSAGE_PERIOD_LEN, log_inter_message_period, "every %lg seconds", period);
proto_tree_add_int_format_value(ptp_tlv_period_tree, hf_ptp_v2_sig_tlv_logInterMessagePeriod_rate, tvb,
if (period > 0) {
rate = 1 / period;
proto_tree_add_int_format_value(ptp_tlv_period_tree, hf_ptp_v2_sig_tlv_logInterMessagePeriod_rate, tvb,
tlv_offset + PTP_V2_SIG_TLV_LOG_INTER_MESSAGE_PERIOD_OFFSET, PTP_V2_SIG_TLV_LOG_INTER_MESSAGE_PERIOD_LEN, log_inter_message_period, "%lg packets/sec", rate);
} else {
proto_tree_add_expert_format(ptp_tlv_period_tree, pinfo, &ei_ptp_v2_period_invalid,
tvb, tlv_offset + PTP_V2_SIG_TLV_LOG_INTER_MESSAGE_PERIOD_OFFSET,
PTP_V2_SIG_TLV_LOG_INTER_MESSAGE_PERIOD_LEN,
"Invalid InterMessagePeriod: %lg", period);
}
/* 16.1.4.2.5 durationField */
proto_tree_add_item(ptp_tlv_tree, hf_ptp_v2_sig_tlv_durationField, tvb,
@ -7541,6 +7564,7 @@ proto_register_ptp(void)
{ &ei_ptp_v2_pdresp_no_pdfup, { "ptp.v2.pdelay_resp_without_fup", PI_PROTOCOL, PI_WARN, "No Follow Up for this Peer Delay Response", EXPFILL }},
{ &ei_ptp_v2_pdresp_twostep, { "ptp.v2.pdelay_resp_two_step_false", PI_PROTOCOL, PI_WARN, "Peer Delay Response with Two Step Flag set to false but Follow Up", EXPFILL }},
{ &ei_ptp_v2_pdfup_no_pdresp, { "ptp.v2.pdelay_fup_without_resp", PI_PROTOCOL, PI_WARN, "No Response for this Peer Delay Follow Up", EXPFILL }},
{ &ei_ptp_v2_period_invalid, { "ptp.v2.period.invalid", PI_PROTOCOL, PI_WARN, "Period invalid", EXPFILL }},
};
expert_module_t* expert_ptp;