diff --git a/src/backend/utils/adt/tsquery.c b/src/backend/utils/adt/tsquery.c
index 27b93eb64d..83f2c602a8 100644
--- a/src/backend/utils/adt/tsquery.c
+++ b/src/backend/utils/adt/tsquery.c
@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/utils/adt/tsquery.c,v 1.3 2007/09/07 15:09:56 teodor Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/adt/tsquery.c,v 1.4 2007/09/07 15:35:10 teodor Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -21,6 +21,7 @@
 #include "tsearch/ts_utils.h"
 #include "utils/memutils.h"
 #include "utils/pg_crc.h"
+#include "nodes/bitmapset.h"
 
 
 struct TSQueryParserStateData
@@ -388,14 +389,14 @@ makepol(TSQueryParserState state,
  * QueryItems must be in polish (prefix) notation. 
  */
 static void
-findoprnd(QueryItem *ptr, int *pos)
+findoprnd(QueryItem *ptr, uint32 *pos)
 {
 	/* since this function recurses, it could be driven to stack overflow. */
 	check_stack_depth();
 
 	if (ptr[*pos].type == QI_VAL ||
 		ptr[*pos].type == QI_VALSTOP) /* need to handle VALSTOP here,
-									   * they haven't been cleansed
+									   * they haven't been cleaned
 									   * away yet.
 									   */
 	{
@@ -451,7 +452,7 @@ parse_tsquery(char *buf,
 	TSQuery		query;
 	int			commonlen;
 	QueryItem  *ptr;
-	int			pos = 0;
+	uint32		pos = 0;
 	ListCell   *cell;
 
 	/* init state */
@@ -792,6 +793,7 @@ tsqueryrecv(PG_FUNCTION_ARGS)
 	QueryItem  *item;
 	int			datalen = 0;
 	char	   *ptr;
+	Bitmapset  *parentset = NULL;
 
 	size = pq_getmsgint(buf, sizeof(uint32));
 	if (size < 0 || size > (MaxAllocSize / sizeof(QueryItem)))
@@ -799,7 +801,7 @@ tsqueryrecv(PG_FUNCTION_ARGS)
 
 	len = HDRSIZETQ + sizeof(QueryItem) * size;
 
-	query = (TSQuery) palloc(len);
+	query = (TSQuery) palloc0(len);
 	query->size = size;
 	item = GETQUERY(query);
 
@@ -814,6 +816,15 @@ tsqueryrecv(PG_FUNCTION_ARGS)
 				item->operand.valcrc = (int32) pq_getmsgint(buf, sizeof(int32));
 				item->operand.length = pq_getmsgint(buf, sizeof(int16));
 
+				/* Check that the weight bitmap is valid */
+				if (item->operand.weight < 0 || item->operand.weight > 0xF)
+					elog(ERROR, "invalid weight bitmap");
+
+				/* XXX: We don't check that the CRC is valid. Actually, if we
+				 * bothered to calculate it to verify, there would be no need
+				 * to transfer it.
+				 */
+
 				/*
 				 * Check that datalen doesn't grow too large. Without the
 				 * check, a malicious client could induce a buffer overflow
@@ -828,7 +839,7 @@ tsqueryrecv(PG_FUNCTION_ARGS)
 					elog(ERROR, "invalid tsquery; total operand length exceeded");
 
 				/* We can calculate distance from datalen, no need to send it
-				 * through the wire. If we did, we would have to check that
+				 * across the wire. If we did, we would have to check that
 				 * it's valid anyway.
 				 */
 				item->operand.distance = datalen;
@@ -842,24 +853,41 @@ tsqueryrecv(PG_FUNCTION_ARGS)
 					item->operator.oper != OP_OR &&
 					item->operator.oper != OP_AND)
 					elog(ERROR, "unknown operator type %d", (int) item->operator.oper);
+
+				/*
+				 * Check that no previous operator node points to the right
+				 * operand. That would mean that the operand node
+				 * has two parents.
+				 */
+				if (bms_is_member(i + 1, parentset))
+					elog(ERROR, "malformed query tree");
+
+				parentset = bms_add_member(parentset, i + 1);
+
 				if(item->operator.oper != OP_NOT)
 				{
-					item->operator.left = (int16) pq_getmsgint(buf, sizeof(int16));
+					uint32 left = (uint32) pq_getmsgint(buf, sizeof(uint32));
+
 					/*
-					 * Sanity checks
+					 * Right operand is implicitly at "this+1". Don't allow
+					 * left to point to the right operand, or to self.
 					 */
-					if (item->operator.left <= 0 || i + item->operator.left >= size)
+					if (left <= 1 || i + left >= size)
 						elog(ERROR, "invalid pointer to left operand");
 
-					/* XXX: Though there's no way to construct a TSQuery that's
-					 * not in polish notation, we don't enforce that for
-					 * queries received from client in binary mode. Is there
-					 * anything that relies on it?
-					 *
-					 * XXX: The tree could be malformed in other ways too,
-					 * a node could have two parents, for example.
+					/*
+					 * Check that no previous operator node points to the left
+					 * operand.
 					 */
+					if (bms_is_member(i + left, parentset))
+						elog(ERROR, "malformed query tree");
+
+					parentset = bms_add_member(parentset, i + left);
+
+					item->operator.left = left;
 				}
+				else
+					item->operator.left = 1; /* do not leave uninitialized fields */
 
 				if (i == size - 1)
 					elog(ERROR, "invalid pointer to right operand");
@@ -871,6 +899,13 @@ tsqueryrecv(PG_FUNCTION_ARGS)
 		item++;
 	}
 
+	/* Now check that each node, except the root, has a parent. We
+	 * already checked above that no node has more than one parent. */
+	if (bms_num_members(parentset) != size - 1 && size != 0)
+		elog(ERROR, "malformed query tree");
+
+	bms_free( parentset );
+
 	query = (TSQuery) repalloc(query, len + datalen);
 
 	item = GETQUERY(query);
diff --git a/src/backend/utils/adt/tsquery_cleanup.c b/src/backend/utils/adt/tsquery_cleanup.c
index 22e6f7c819..6ab58228b5 100644
--- a/src/backend/utils/adt/tsquery_cleanup.c
+++ b/src/backend/utils/adt/tsquery_cleanup.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/utils/adt/tsquery_cleanup.c,v 1.2 2007/09/07 15:09:56 teodor Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/adt/tsquery_cleanup.c,v 1.3 2007/09/07 15:35:10 teodor Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -57,6 +57,9 @@ typedef struct
 static void
 plainnode(PLAINTREE * state, NODE * node)
 {
+	/* since this function recurses, it could be driven to stack overflow. */
+	check_stack_depth();
+
 	if (state->cur == state->len)
 	{
 		state->len *= 2;
@@ -107,6 +110,9 @@ plaintree(NODE * root, int *len)
 static void
 freetree(NODE * node)
 {
+	/* since this function recurses, it could be driven to stack overflow. */
+	check_stack_depth();
+
 	if (!node)
 		return;
 	if (node->left)
@@ -125,6 +131,9 @@ freetree(NODE * node)
 static NODE *
 clean_NOT_intree(NODE * node)
 {
+	/* since this function recurses, it could be driven to stack overflow. */
+	check_stack_depth();
+
 	if (node->valnode->type == QI_VAL)
 		return node;
 
@@ -203,6 +212,9 @@ clean_fakeval_intree(NODE * node, char *result)
 	char		lresult = V_UNKNOWN,
 				rresult = V_UNKNOWN;
 
+	/* since this function recurses, it could be driven to stack overflow. */
+	check_stack_depth();
+
 	if (node->valnode->type == QI_VAL)
 		return node;
 	else 
diff --git a/src/backend/utils/adt/tsquery_rewrite.c b/src/backend/utils/adt/tsquery_rewrite.c
index db2fe6c53e..d733a51d8e 100644
--- a/src/backend/utils/adt/tsquery_rewrite.c
+++ b/src/backend/utils/adt/tsquery_rewrite.c
@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/utils/adt/tsquery_rewrite.c,v 1.2 2007/09/07 15:09:56 teodor Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/adt/tsquery_rewrite.c,v 1.3 2007/09/07 15:35:10 teodor Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -22,6 +22,9 @@
 static int
 addone(int *counters, int last, int total)
 {
+	/* since this function recurses, it could be driven to stack overflow. */
+	check_stack_depth();
+
 	counters[last]++;
 	if (counters[last] >= total)
 	{
@@ -173,6 +176,9 @@ findeq(QTNode *node, QTNode *ex, QTNode *subs, bool *isfind)
 static QTNode *
 dofindsubquery(QTNode *root, QTNode *ex, QTNode *subs, bool *isfind)
 {
+	/* since this function recurses, it could be driven to stack overflow. */
+	check_stack_depth();
+
 	root = findeq(root, ex, subs, isfind);
 
 	if (root && (root->flags & QTN_NOCHANGE) == 0 && root->valnode->type == QI_OPR)
diff --git a/src/backend/utils/adt/tsquery_util.c b/src/backend/utils/adt/tsquery_util.c
index e378661488..60de44cc6f 100644
--- a/src/backend/utils/adt/tsquery_util.c
+++ b/src/backend/utils/adt/tsquery_util.c
@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/utils/adt/tsquery_util.c,v 1.2 2007/09/07 15:09:56 teodor Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/adt/tsquery_util.c,v 1.3 2007/09/07 15:35:10 teodor Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -22,6 +22,9 @@ QT2QTN(QueryItem * in, char *operand)
 {
 	QTNode	   *node = (QTNode *) palloc0(sizeof(QTNode));
 
+	/* since this function recurses, it could be driven to stack overflow. */
+	check_stack_depth();
+
 	node->valnode = in;
 
 	if (in->type == QI_OPR)
@@ -53,6 +56,9 @@ QTNFree(QTNode * in)
 	if (!in)
 		return;
 
+	/* since this function recurses, it could be driven to stack overflow. */
+	check_stack_depth();
+
 	if (in->valnode->type == QI_VAL && in->word && (in->flags & QTN_WORDFREE) != 0)
 		pfree(in->word);
 
@@ -79,6 +85,9 @@ QTNFree(QTNode * in)
 int
 QTNodeCompare(QTNode * an, QTNode * bn)
 {
+	/* since this function recurses, it could be driven to stack overflow. */
+	check_stack_depth();
+
 	if (an->valnode->type != bn->valnode->type)
 		return (an->valnode->type > bn->valnode->type) ? -1 : 1;
 	
@@ -133,6 +142,9 @@ QTNSort(QTNode * in)
 {
 	int			i;
 
+	/* since this function recurses, it could be driven to stack overflow. */
+	check_stack_depth();
+
 	if (in->valnode->type != QI_OPR)
 		return;
 
@@ -165,6 +177,9 @@ QTNTernary(QTNode * in)
 {
 	int			i;
 
+	/* since this function recurses, it could be driven to stack overflow. */
+	check_stack_depth();
+
 	if (in->valnode->type != QI_OPR)
 		return;
 
@@ -205,6 +220,9 @@ QTNBinary(QTNode * in)
 {
 	int			i;
 
+	/* since this function recurses, it could be driven to stack overflow. */
+	check_stack_depth();
+
 	if (in->valnode->type != QI_OPR)
 		return;
 
@@ -244,6 +262,9 @@ QTNBinary(QTNode * in)
 static void
 cntsize(QTNode * in, int *sumlen, int *nnode)
 {
+	/* since this function recurses, it could be driven to stack overflow. */
+	check_stack_depth();
+
 	*nnode += 1;
 	if (in->valnode->type == QI_OPR)
 	{
@@ -268,6 +289,9 @@ typedef struct
 static void
 fillQT(QTN2QTState *state, QTNode *in)
 {
+	/* since this function recurses, it could be driven to stack overflow. */
+	check_stack_depth();
+
 	if (in->valnode->type == QI_VAL)
 	{
 		memcpy(state->curitem, in->valnode, sizeof(QueryOperand));
@@ -325,7 +349,12 @@ QTN2QT(QTNode *in)
 QTNode *
 QTNCopy(QTNode *in)
 {
-	QTNode	   *out = (QTNode *) palloc(sizeof(QTNode));
+	QTNode	   *out;
+
+	/* since this function recurses, it could be driven to stack overflow. */
+	check_stack_depth();
+
+	out = (QTNode *) palloc(sizeof(QTNode));
 
 	*out = *in;
 	out->valnode = (QueryItem *) palloc(sizeof(QueryItem));
diff --git a/src/backend/utils/adt/tsrank.c b/src/backend/utils/adt/tsrank.c
index d48e9b4a47..30ccfa3f61 100644
--- a/src/backend/utils/adt/tsrank.c
+++ b/src/backend/utils/adt/tsrank.c
@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/utils/adt/tsrank.c,v 1.2 2007/09/07 15:09:56 teodor Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/adt/tsrank.c,v 1.3 2007/09/07 15:35:10 teodor Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -508,6 +508,10 @@ Cover(DocRepresentation *doc, int len, TSQuery query, Extention *ext)
 	int			i;
 	bool		found = false;
 
+	/* since this function recurses, it could be driven to stack overflow.
+	 * (though any decent compiler will optimize away the tail-recursion.   */
+	check_stack_depth();
+
 	reset_istrue_flag(query);
 
 	ext->p = 0x7fffffff;
diff --git a/src/include/tsearch/ts_type.h b/src/include/tsearch/ts_type.h
index 91d724ef1c..15aa9f5c6e 100644
--- a/src/include/tsearch/ts_type.h
+++ b/src/include/tsearch/ts_type.h
@@ -5,7 +5,7 @@
  *
  * Copyright (c) 1998-2007, PostgreSQL Global Development Group
  *
- * $PostgreSQL: pgsql/src/include/tsearch/ts_type.h,v 1.2 2007/09/07 15:09:56 teodor Exp $
+ * $PostgreSQL: pgsql/src/include/tsearch/ts_type.h,v 1.3 2007/09/07 15:35:11 teodor Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -160,7 +160,13 @@ typedef struct
 {
 	QueryItemType		type;	/* operand or kind of operator (ts_tokentype) */
 	int8		weight;			/* weights of operand to search. It's a bitmask of allowed weights.
-								 * if it =0 then any weight are allowed */
+								 * if it =0 then any weight are allowed.
+								 * Weights and bit map:
+								 * A: 1<<3
+								 * B: 1<<2
+								 * C: 1<<1
+								 * D: 1<<0
+								 */
 	int32	valcrc;				/* XXX: pg_crc32 would be a more appropriate data type, 
 								 * but we use comparisons to signed integers in the code. 
 								 * They would need to be changed as well. */
@@ -182,7 +188,7 @@ typedef struct
 {
 	QueryItemType	type;
 	int8		oper;		/* see above */
-	int16		left;		/* pointer to left operand. Right operand is
+	uint32		left;		/* pointer to left operand. Right operand is
 							 * item + 1, left operand is placed
 							 * item+item->left */
 } QueryOperator;