143 lines
6.1 KiB
Diff
143 lines
6.1 KiB
Diff
From 0f27a83c5692b2afebe6e6934c1051f76aa2ecf9 Mon Sep 17 00:00:00 2001
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From: Jason Cohen <kryojenik2@gmail.com>
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Date: Wed, 31 Aug 2022 11:10:17 -0500
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Subject: [PATCH] f5ethtrailer: Improve "old-style" heuristic
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Remove a chance for an infinate loop in the disection heuristic.
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---
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epan/dissectors/packet-f5ethtrailer.c | 108 +++++++++++++-------------
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1 file changed, 56 insertions(+), 52 deletions(-)
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diff --git a/epan/dissectors/packet-f5ethtrailer.c b/epan/dissectors/packet-f5ethtrailer.c
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index b2ba8f899d..915348ea83 100644
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--- a/epan/dissectors/packet-f5ethtrailer.c
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+++ b/epan/dissectors/packet-f5ethtrailer.c
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@@ -2751,69 +2751,73 @@ dissect_dpt_trailer(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *d
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static gint
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dissect_old_trailer(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data)
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{
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- proto_tree *type_tree = NULL;
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- proto_item *ti = NULL;
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guint offset = 0;
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- guint processed = 0;
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- f5eth_tap_data_t *tdata = (f5eth_tap_data_t *)data;
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- guint8 type;
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- guint8 len;
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- guint8 ver;
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/* While we still have data in the trailer. For old format trailers, this needs
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* type, length, version (3 bytes) and for new format trailers, the magic header (4 bytes).
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* All old format trailers are at least 4 bytes long, so just check for length of magic.
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*/
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- while (tvb_reported_length_remaining(tvb, offset)) {
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- type = tvb_get_guint8(tvb, offset);
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- len = tvb_get_guint8(tvb, offset + F5_OFF_LENGTH) + F5_OFF_VERSION;
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- ver = tvb_get_guint8(tvb, offset + F5_OFF_VERSION);
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-
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- if (len <= tvb_reported_length_remaining(tvb, offset) && type >= F5TYPE_LOW
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- && type <= F5TYPE_HIGH && len >= F5_MIN_SANE && len <= F5_MAX_SANE
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- && ver <= F5TRAILER_VER_MAX) {
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- /* Parse out the specified trailer. */
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- switch (type) {
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- case F5TYPE_LOW:
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- ti = proto_tree_add_item(tree, hf_low_id, tvb, offset, len, ENC_NA);
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- type_tree = proto_item_add_subtree(ti, ett_f5ethtrailer_low);
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-
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- processed = dissect_low_trailer(tvb, pinfo, type_tree, offset, len, ver, tdata);
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- if (processed > 0) {
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- tdata->trailer_len += processed;
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- tdata->noise_low = 1;
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- }
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- break;
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- case F5TYPE_MED:
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- ti = proto_tree_add_item(tree, hf_med_id, tvb, offset, len, ENC_NA);
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- type_tree = proto_item_add_subtree(ti, ett_f5ethtrailer_med);
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-
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- processed = dissect_med_trailer(tvb, pinfo, type_tree, offset, len, ver, tdata);
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- if (processed > 0) {
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- tdata->trailer_len += processed;
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- tdata->noise_med = 1;
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- }
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- break;
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- case F5TYPE_HIGH:
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- ti = proto_tree_add_item(tree, hf_high_id, tvb, offset, len, ENC_NA);
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- type_tree = proto_item_add_subtree(ti, ett_f5ethtrailer_high);
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-
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- processed =
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- dissect_high_trailer(tvb, pinfo, type_tree, offset, len, ver, tdata);
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- if (processed > 0) {
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- tdata->trailer_len += processed;
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- tdata->noise_high = 1;
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- }
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- break;
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+ while (tvb_reported_length_remaining(tvb, offset) >= F5_MIN_SANE) {
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+ /* length field does not include the type and length bytes. Add them back in */
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+ guint8 len = tvb_get_guint8(tvb, offset + F5_OFF_LENGTH) + F5_OFF_VERSION;
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+ if (len > tvb_reported_length_remaining(tvb, offset)
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+ || len < F5_MIN_SANE || len > F5_MAX_SANE) {
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+ /* Invalid length - either a malformed trailer, corrupt packet, or not f5ethtrailer */
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+ return offset;
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+ }
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+ guint8 type = tvb_get_guint8(tvb, offset);
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+ guint8 ver = tvb_get_guint8(tvb, offset + F5_OFF_VERSION);
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+
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+ /* Parse out the specified trailer. */
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+ proto_tree *type_tree = NULL;
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+ proto_item *ti = NULL;
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+ f5eth_tap_data_t *tdata = (f5eth_tap_data_t *)data;
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+ guint processed = 0;
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+
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+ switch (type) {
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+ case F5TYPE_LOW:
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+ ti = proto_tree_add_item(tree, hf_low_id, tvb, offset, len, ENC_NA);
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+ type_tree = proto_item_add_subtree(ti, ett_f5ethtrailer_low);
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+
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+ processed = dissect_low_trailer(tvb, pinfo, type_tree, offset, len, ver, tdata);
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+ if (processed > 0) {
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+ tdata->trailer_len += processed;
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+ tdata->noise_low = 1;
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}
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- if (processed == 0) {
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- proto_item_set_len(ti, 1);
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- return offset;
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+ break;
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+ case F5TYPE_MED:
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+ ti = proto_tree_add_item(tree, hf_med_id, tvb, offset, len, ENC_NA);
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+ type_tree = proto_item_add_subtree(ti, ett_f5ethtrailer_med);
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+
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+ processed = dissect_med_trailer(tvb, pinfo, type_tree, offset, len, ver, tdata);
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+ if (processed > 0) {
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+ tdata->trailer_len += processed;
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+ tdata->noise_med = 1;
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+ }
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+ break;
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+ case F5TYPE_HIGH:
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+ ti = proto_tree_add_item(tree, hf_high_id, tvb, offset, len, ENC_NA);
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+ type_tree = proto_item_add_subtree(ti, ett_f5ethtrailer_high);
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+
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+ processed =
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+ dissect_high_trailer(tvb, pinfo, type_tree, offset, len, ver, tdata);
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+ if (processed > 0) {
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+ tdata->trailer_len += processed;
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+ tdata->noise_high = 1;
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}
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+ break;
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+ default:
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+ /* Unknown type - malformed trailer, corrupt packet, or not f5ethtrailer - bali out*/
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+ return offset;
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+ }
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+ if (processed == 0) {
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+ /* couldn't process trailer - bali out */
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+ proto_item_set_len(ti, 1);
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+ return offset;
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}
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offset += processed;
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}
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-return offset;
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+ return offset;
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} /* dissect_old_trailer() */
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/*---------------------------------------------------------------------------*/
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--
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GitLab
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