windows-common: don't THROW() an exception from a dissector

Bring up an expert info instead of throwing an exception. Point to the
item that contains the invalid offset. Exit normally, returning the
number of bytes we consumed so far.

Change-Id: I97826a41c6713a97404ca437b9be60c77e009918
Reviewed-on: https://code.wireshark.org/review/23507
Reviewed-by: Martin Kaiser <wireshark@kaiser.cx>
Petri-Dish: Martin Kaiser <wireshark@kaiser.cx>
Tested-by: Petri Dish Buildbot <buildbot-no-reply@wireshark.org>
Reviewed-by: Michael Mann <mmann78@netscape.net>

1 files changed, 22 insertions, 20 deletions

diff --git a/epan/dissectors/packet-windows-common.c b/epan/dissectors/packet-windows-common.c
index 4974ec9fa9..4dff2f2efd 100644
--- a/epan/dissectors/packet-windows-common.c
+++ b/epan/dissectors/packet-windows-common.c
@@ -104,6 +104,7 @@ static expert_field ei_nt_ace_extends_beyond_capture = EI_INIT;
 static expert_field ei_nt_group_sid_beyond_reassembled_data = EI_INIT;
 static expert_field ei_nt_group_sid_beyond_captured_data = EI_INIT;
 static expert_field ei_nt_owner_sid_beyond_captured_data = EI_INIT;
+static expert_field ei_nt_item_offs_out_of_range = EI_INIT;
 
 
 /* WERR error codes */
@@ -2363,9 +2364,13 @@ dissect_nt_sec_desc(tvbuff_t *tvb, int offset_a, packet_info *pinfo,
 	volatile int end_offset;
 	volatile int item_offset;
 	guint32 owner_sid_offset;
+	proto_item *it_owner_sid_offs = NULL;
 	volatile guint32 group_sid_offset;
+	proto_item *it_gr_sid_offs = NULL;
 	volatile guint32 sacl_offset;
+	proto_item *it_sacl_offs = NULL;
 	volatile guint32 dacl_offset;
+	proto_item *it_dacl_offs = NULL;
 
 	tree = proto_tree_add_subtree(parent_tree, tvb, offset_v, -1,
 				   ett_nt_sec_desc, &item, "NT Security Descriptor");
@@ -2388,7 +2393,7 @@ dissect_nt_sec_desc(tvbuff_t *tvb, int offset_a, packet_info *pinfo,
 	    proto_tree_add_uint_format_value(tree, hf_nt_offset_to_owner_sid, tvb, offset_v, 4, owner_sid_offset, "%u (bogus, must be >= 20)", owner_sid_offset);
 	    owner_sid_offset = 0;
 	  } else
-	    proto_tree_add_item(tree, hf_nt_offset_to_owner_sid, tvb, offset_v, 4, ENC_LITTLE_ENDIAN);
+	    it_owner_sid_offs = proto_tree_add_item(tree, hf_nt_offset_to_owner_sid, tvb, offset_v, 4, ENC_LITTLE_ENDIAN);
 	  offset_v += 4;
 
 	  /* offset to group sid */
@@ -2398,7 +2403,7 @@ dissect_nt_sec_desc(tvbuff_t *tvb, int offset_a, packet_info *pinfo,
 	    proto_tree_add_uint_format_value(tree, hf_nt_offset_to_group_sid, tvb, offset_v, 4, group_sid_offset, "%u (bogus, must be >= 20)", group_sid_offset);
 	    group_sid_offset = 0;
 	  } else
-	    proto_tree_add_item(tree, hf_nt_offset_to_group_sid, tvb, offset_v, 4, ENC_LITTLE_ENDIAN);
+	    it_gr_sid_offs = proto_tree_add_item(tree, hf_nt_offset_to_group_sid, tvb, offset_v, 4, ENC_LITTLE_ENDIAN);
 	  offset_v += 4;
 
 	  /* offset to sacl */
@@ -2408,7 +2413,7 @@ dissect_nt_sec_desc(tvbuff_t *tvb, int offset_a, packet_info *pinfo,
 	    proto_tree_add_uint_format_value(tree, hf_nt_offset_to_sacl, tvb, offset_v, 4, sacl_offset, "%u (bogus, must be >= 20)", sacl_offset);
 	    sacl_offset = 0;
 	  } else
-	    proto_tree_add_item(tree, hf_nt_offset_to_sacl, tvb, offset_v, 4, ENC_LITTLE_ENDIAN);
+	    it_sacl_offs = proto_tree_add_item(tree, hf_nt_offset_to_sacl, tvb, offset_v, 4, ENC_LITTLE_ENDIAN);
 	  offset_v += 4;
 
 	  /* offset to dacl */
@@ -2418,7 +2423,7 @@ dissect_nt_sec_desc(tvbuff_t *tvb, int offset_a, packet_info *pinfo,
 	    proto_tree_add_uint_format_value(tree, hf_nt_offset_to_dacl, tvb, offset_v, 4, dacl_offset, "%u (bogus, must be >= 20)", dacl_offset);
 	    dacl_offset = 0;
 	  } else
-	    proto_tree_add_item(tree, hf_nt_offset_to_dacl, tvb, offset_v, 4, ENC_LITTLE_ENDIAN);
+	    it_dacl_offs = proto_tree_add_item(tree, hf_nt_offset_to_dacl, tvb, offset_v, 4, ENC_LITTLE_ENDIAN);
 	  offset_v += 4;
 
 	  end_offset = offset_v;
@@ -2427,10 +2432,9 @@ dissect_nt_sec_desc(tvbuff_t *tvb, int offset_a, packet_info *pinfo,
 	  if(owner_sid_offset){
 	    item_offset = start_offset+owner_sid_offset;
 	    if (item_offset < start_offset) {
-	      /*
-	       * Overflow - throw an exception.
-	       */
-	      THROW(ReportedBoundsError);
+		    expert_add_info(pinfo, it_owner_sid_offs,
+				    &ei_nt_item_offs_out_of_range);
+		    break;
 	    }
 	    TRY{
 	      offset_v = dissect_nt_sid(tvb, item_offset, tree, "Owner", NULL, -1);
@@ -2453,10 +2457,9 @@ dissect_nt_sec_desc(tvbuff_t *tvb, int offset_a, packet_info *pinfo,
 	  if(group_sid_offset){
 	    item_offset = start_offset+group_sid_offset;
 	    if (item_offset < start_offset) {
-	      /*
-	       * Overflow - throw an exception.
-	       */
-	      THROW(ReportedBoundsError);
+		    expert_add_info(pinfo, it_gr_sid_offs,
+				    &ei_nt_item_offs_out_of_range);
+		    break;
 	    }
 	    TRY {
 	      offset_v = dissect_nt_sid(tvb, item_offset, tree, "Group", NULL, -1);
@@ -2479,10 +2482,9 @@ dissect_nt_sec_desc(tvbuff_t *tvb, int offset_a, packet_info *pinfo,
 	  if(sacl_offset){
 	    item_offset = start_offset+sacl_offset;
 	    if (item_offset < start_offset) {
-	      /*
-	       * Overflow - throw an exception.
-	       */
-	      THROW(ReportedBoundsError);
+		    expert_add_info(pinfo, it_sacl_offs,
+				    &ei_nt_item_offs_out_of_range);
+		    break;
 	    }
 	    offset_v = dissect_nt_acl(tvb, item_offset, pinfo, tree,
 				    drep, "System (SACL)", ami);
@@ -2494,10 +2496,9 @@ dissect_nt_sec_desc(tvbuff_t *tvb, int offset_a, packet_info *pinfo,
 	  if(dacl_offset){
 	    item_offset = start_offset+dacl_offset;
 	    if (item_offset < start_offset) {
-	      /*
-	       * Overflow - throw an exception.
-	       */
-	      THROW(ReportedBoundsError);
+		    expert_add_info(pinfo, it_dacl_offs,
+				    &ei_nt_item_offs_out_of_range);
+		    break;
 	    }
 	    offset_v = dissect_nt_acl(tvb, item_offset, pinfo, tree,
 				    drep, "User (DACL)", ami);
@@ -2905,6 +2906,7 @@ proto_do_register_windows_common(int proto_smb)
 		{ &ei_nt_owner_sid_beyond_reassembled_data, { "nt.owner_sid.beyond_reassembled_data", PI_MALFORMED, PI_ERROR, "Owner SID beyond end of reassembled data", EXPFILL }},
 		{ &ei_nt_group_sid_beyond_captured_data, { "nt.group_sid.beyond_captured_data", PI_MALFORMED, PI_ERROR, "Group SID beyond end of captured data", EXPFILL }},
 		{ &ei_nt_group_sid_beyond_reassembled_data, { "nt.group_sid.beyond_reassembled_data", PI_MALFORMED, PI_ERROR, "Group SID beyond end of reassembled data", EXPFILL }},
+		{ &ei_nt_item_offs_out_of_range, { "nt.item_offset.out_of_range", PI_MALFORMED, PI_ERROR, "Item offset is out of range", EXPFILL }},
 	};
 
 	expert_module_t* expert_nt;