Predict integer overflow to avoid buffer overruns.

nmisch · nmisch · commit 98be8a6eaa9f · 2014-02-17T09:33:39.000-05:00
Several functions, mostly type input functions, calculated an allocation size such that the calculation wrapped to a small positive value when arguments implied a sufficiently-large requirement. Writes past the end of the inadvertent small allocation followed shortly thereafter. Coverity identified the path_in() vulnerability; code inspection led to the rest. In passing, add check_stack_depth() to prevent stack overflow in related functions. Back-patch to 8.4 (all supported versions). The non-comment hstore changes touch code that did not exist in 8.4, so that part stops at 9.0. Noah Misch and Heikki Linnakangas, reviewed by Tom Lane. Security: CVE-2014-0064
diff --git a/contrib/intarray/_int.h b/contrib/intarray/_int.h
@@ -5,6 +5,7 @@
 #define ___INT_H__
 
 #include "utils/array.h"
+#include "utils/memutils.h"
 
 /* number ranges for compression */
 #define MAXNUMRANGE 100
@@ -142,6 +143,7 @@ typedef struct
 
 #define HDRSIZEQT	(VARHDRSZ + sizeof(int4))
 #define COMPUTESIZE(size)	( HDRSIZEQT + size * sizeof(ITEM) )
+#define QUERYTYPEMAXITEMS	((MaxAllocSize - HDRSIZEQT) / sizeof(ITEM))
 #define GETQUERY(x)  (ITEM*)( (char*)(x)+HDRSIZEQT )
 
 #define END		0
diff --git a/contrib/intarray/_int_bool.c b/contrib/intarray/_int_bool.c
@@ -416,6 +416,9 @@ boolop(PG_FUNCTION_ARGS)
 static void
 findoprnd(ITEM *ptr, int4 *pos)
 {
+	/* since this function recurses, it could be driven to stack overflow. */
+	check_stack_depth();
+
 #ifdef BS_DEBUG
 	elog(DEBUG3, (ptr[*pos].type == OPR) ?
 		 "%d  %c" : "%d  %d", *pos, ptr[*pos].val);
@@ -476,7 +479,13 @@ bqarr_in(PG_FUNCTION_ARGS)
 				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
 				 errmsg("empty query")));
 
+	if (state.num > QUERYTYPEMAXITEMS)
+		ereport(ERROR,
+				(errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
+		errmsg("number of query items (%d) exceeds the maximum allowed (%d)",
+			   state.num, (int) QUERYTYPEMAXITEMS)));
 	commonlen = COMPUTESIZE(state.num);
+
 	query = (QUERYTYPE *) palloc(commonlen);
 	SET_VARSIZE(query, commonlen);
 	query->size = state.num;
diff --git a/contrib/ltree/ltree.h b/contrib/ltree/ltree.h
@@ -6,6 +6,7 @@
 #include "postgres.h"
 #include "fmgr.h"
 #include "tsearch/ts_locale.h"
+#include "utils/memutils.h"
 
 typedef struct
 {
@@ -112,6 +113,8 @@ typedef struct
 
 #define HDRSIZEQT		MAXALIGN(VARHDRSZ + sizeof(int4))
 #define COMPUTESIZE(size,lenofoperand)	( HDRSIZEQT + (size) * sizeof(ITEM) + (lenofoperand) )
+#define LTXTQUERY_TOO_BIG(size,lenofoperand) \
+	((size) > (MaxAllocSize - HDRSIZEQT - (lenofoperand)) / sizeof(ITEM))
 #define GETQUERY(x)  (ITEM*)( (char*)(x)+HDRSIZEQT )
 #define GETOPERAND(x)	( (char*)GETQUERY(x) + ((ltxtquery*)x)->size * sizeof(ITEM) )
 
diff --git a/contrib/ltree/ltree_io.c b/contrib/ltree/ltree_io.c
@@ -8,6 +8,7 @@
 #include <ctype.h>
 
 #include "ltree.h"
+#include "utils/memutils.h"
 #include "crc32.h"
 
 PG_FUNCTION_INFO_V1(ltree_in);
@@ -64,6 +65,11 @@ ltree_in(PG_FUNCTION_ARGS)
 		ptr += charlen;
 	}
 
+	if (num + 1 > MaxAllocSize / sizeof(nodeitem))
+		ereport(ERROR,
+				(errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
+			 errmsg("number of levels (%d) exceeds the maximum allowed (%d)",
+					num + 1, (int) (MaxAllocSize / sizeof(nodeitem)))));
 	list = lptr = (nodeitem *) palloc(sizeof(nodeitem) * (num + 1));
 	ptr = buf;
 	while (*ptr)
@@ -228,6 +234,11 @@ lquery_in(PG_FUNCTION_ARGS)
 	}
 
 	num++;
+	if (num > MaxAllocSize / ITEMSIZE)
+		ereport(ERROR,
+				(errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
+			 errmsg("number of levels (%d) exceeds the maximum allowed (%d)",
+					num, (int) (MaxAllocSize / ITEMSIZE))));
 	curqlevel = tmpql = (lquery_level *) palloc0(ITEMSIZE * num);
 	ptr = buf;
 	while (*ptr)
diff --git a/contrib/ltree/ltxtquery_io.c b/contrib/ltree/ltxtquery_io.c
@@ -9,6 +9,7 @@
 
 #include "crc32.h"
 #include "ltree.h"
+#include "miscadmin.h"
 
 PG_FUNCTION_INFO_V1(ltxtq_in);
 Datum		ltxtq_in(PG_FUNCTION_ARGS);
@@ -213,6 +214,9 @@ makepol(QPRS_STATE *state)
 	int4		lenstack = 0;
 	uint16		flag = 0;
 
+	/* since this function recurses, it could be driven to stack overflow */
+	check_stack_depth();
+
 	while ((type = gettoken_query(state, &val, &lenval, &strval, &flag)) != END)
 	{
 		switch (type)
@@ -277,6 +281,9 @@ makepol(QPRS_STATE *state)
 static void
 findoprnd(ITEM *ptr, int4 *pos)
 {
+	/* since this function recurses, it could be driven to stack overflow. */
+	check_stack_depth();
+
 	if (ptr[*pos].type == VAL || ptr[*pos].type == VALTRUE)
 	{
 		ptr[*pos].left = 0;
@@ -341,8 +348,12 @@ queryin(char *buf)
 				 errmsg("syntax error"),
 				 errdetail("Empty query.")));
 
-	/* make finish struct */
+	if (LTXTQUERY_TOO_BIG(state.num, state.sumlen))
+		ereport(ERROR,
+				(errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
+				 errmsg("ltxtquery is too large")));
 	commonlen = COMPUTESIZE(state.num, state.sumlen);
+
 	query = (ltxtquery *) palloc(commonlen);
 	SET_VARSIZE(query, commonlen);
 	query->size = state.num;
diff --git a/src/backend/utils/adt/geo_ops.c b/src/backend/utils/adt/geo_ops.c
@@ -1401,6 +1401,7 @@ path_in(PG_FUNCTION_ARGS)
 	char	   *s;
 	int			npts;
 	int			size;
+	int			base_size;
 	int			depth = 0;
 
 	if ((npts = pair_count(str, ',')) <= 0)
@@ -1419,7 +1420,15 @@ path_in(PG_FUNCTION_ARGS)
 		depth++;
 	}
 
-	size = offsetof(PATH, p[0]) +sizeof(path->p[0]) * npts;
+	base_size = sizeof(path->p[0]) * npts;
+	size = offsetof(PATH, p[0]) + base_size;
+
+	/* Check for integer overflow */
+	if (base_size / npts != sizeof(path->p[0]) || size <= base_size)
+		ereport(ERROR,
+				(errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
+				 errmsg("too many points requested")));
+
 	path = (PATH *) palloc(size);
 
 	SET_VARSIZE(path, size);
@@ -3439,6 +3448,7 @@ poly_in(PG_FUNCTION_ARGS)
 	POLYGON    *poly;
 	int			npts;
 	int			size;
+	int			base_size;
 	int			isopen;
 	char	   *s;
 
@@ -3447,7 +3457,15 @@ poly_in(PG_FUNCTION_ARGS)
 				(errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
 			  errmsg("invalid input syntax for type polygon: \"%s\"", str)));
 
-	size = offsetof(POLYGON, p[0]) +sizeof(poly->p[0]) * npts;
+	base_size = sizeof(poly->p[0]) * npts;
+	size = offsetof(POLYGON, p[0]) + base_size;
+
+	/* Check for integer overflow */
+	if (base_size / npts != sizeof(poly->p[0]) || size <= base_size)
+		ereport(ERROR,
+				(errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
+				 errmsg("too many points requested")));
+
 	poly = (POLYGON *) palloc0(size);	/* zero any holes */
 
 	SET_VARSIZE(poly, size);
@@ -4216,6 +4234,10 @@ path_poly(PG_FUNCTION_ARGS)
 				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
 				 errmsg("open path cannot be converted to polygon")));
 
+	/*
+	 * Never overflows: the old size fit in MaxAllocSize, and the new size is
+	 * just a small constant larger.
+	 */
 	size = offsetof(POLYGON, p[0]) +sizeof(poly->p[0]) * path->npts;
 	poly = (POLYGON *) palloc(size);
 
@@ -4321,6 +4343,10 @@ poly_path(PG_FUNCTION_ARGS)
 	int			size;
 	int			i;
 
+	/*
+	 * Never overflows: the old size fit in MaxAllocSize, and the new size is
+	 * smaller by a small constant.
+	 */
 	size = offsetof(PATH, p[0]) +sizeof(path->p[0]) * poly->npts;
 	path = (PATH *) palloc(size);
 
diff --git a/src/backend/utils/adt/tsquery.c b/src/backend/utils/adt/tsquery.c
@@ -517,8 +517,13 @@ parse_tsquery(char *buf,
 		return query;
 	}
 
-	/* Pack the QueryItems in the final TSQuery struct to return to caller */
+	if (TSQUERY_TOO_BIG(list_length(state.polstr), state.sumlen))
+		ereport(ERROR,
+				(errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
+				 errmsg("tsquery is too large")));
 	commonlen = COMPUTESIZE(list_length(state.polstr), state.sumlen);
+
+	/* Pack the QueryItems in the final TSQuery struct to return to caller */
 	query = (TSQuery) palloc0(commonlen);
 	SET_VARSIZE(query, commonlen);
 	query->size = list_length(state.polstr);
diff --git a/src/backend/utils/adt/tsquery_util.c b/src/backend/utils/adt/tsquery_util.c
@@ -334,6 +334,11 @@ QTN2QT(QTNode *in)
 	QTN2QTState state;
 
 	cntsize(in, &sumlen, &nnode);
+
+	if (TSQUERY_TOO_BIG(nnode, sumlen))
+		ereport(ERROR,
+				(errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
+				 errmsg("tsquery is too large")));
 	len = COMPUTESIZE(nnode, sumlen);
 
 	out = (TSQuery) palloc0(len);
diff --git a/src/backend/utils/adt/txid.c b/src/backend/utils/adt/txid.c
@@ -26,6 +26,7 @@
 #include "funcapi.h"
 #include "libpq/pqformat.h"
 #include "utils/builtins.h"
+#include "utils/memutils.h"
 #include "utils/snapmgr.h"
 
 
@@ -70,6 +71,8 @@ typedef struct
 
 #define TXID_SNAPSHOT_SIZE(nxip) \
 	(offsetof(TxidSnapshot, xip) + sizeof(txid) * (nxip))
+#define TXID_SNAPSHOT_MAX_NXIP \
+	((MaxAllocSize - offsetof(TxidSnapshot, xip)) / sizeof(txid))
 
 /*
  * Epoch values from xact.c
@@ -445,20 +448,12 @@ txid_snapshot_recv(PG_FUNCTION_ARGS)
 	txid		last = 0;
 	int			nxip;
 	int			i;
-	int			avail;
-	int			expect;
 	txid		xmin,
 				xmax;
 
-	/*
-	 * load nxip and check for nonsense.
-	 *
-	 * (nxip > avail) check is against int overflows in 'expect'.
-	 */
+	/* load and validate nxip */
 	nxip = pq_getmsgint(buf, 4);
-	avail = buf->len - buf->cursor;
-	expect = 8 + 8 + nxip * 8;
-	if (nxip < 0 || nxip > avail || expect > avail)
+	if (nxip < 0 || nxip > TXID_SNAPSHOT_MAX_NXIP)
 		goto bad_format;
 
 	xmin = pq_getmsgint64(buf);
diff --git a/src/backend/utils/adt/varbit.c b/src/backend/utils/adt/varbit.c
@@ -138,12 +138,22 @@ bit_in(PG_FUNCTION_ARGS)
 		sp = input_string;
 	}
 
+	/*
+	 * Determine bitlength from input string.  MaxAllocSize ensures a regular
+	 * input is small enough, but we must check hex input.
+	 */
 	slen = strlen(sp);
-	/* Determine bitlength from input string */
 	if (bit_not_hex)
 		bitlen = slen;
 	else
+	{
+		if (slen > VARBITMAXLEN / 4)
+			ereport(ERROR,
+					(errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
+				 errmsg("bit string length exceeds the maximum allowed (%d)",
+						VARBITMAXLEN)));
 		bitlen = slen * 4;
+	}
 
 	/*
 	 * Sometimes atttypmod is not supplied. If it is supplied we need to make
@@ -436,12 +446,22 @@ varbit_in(PG_FUNCTION_ARGS)
 		sp = input_string;
 	}
 
+	/*
+	 * Determine bitlength from input string.  MaxAllocSize ensures a regular
+	 * input is small enough, but we must check hex input.
+	 */
 	slen = strlen(sp);
-	/* Determine bitlength from input string */
 	if (bit_not_hex)
 		bitlen = slen;
 	else
+	{
+		if (slen > VARBITMAXLEN / 4)
+			ereport(ERROR,
+					(errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
+				 errmsg("bit string length exceeds the maximum allowed (%d)",
+						VARBITMAXLEN)));
 		bitlen = slen * 4;
+	}
 
 	/*
 	 * Sometimes atttypmod is not supplied. If it is supplied we need to make
@@ -520,6 +540,9 @@ varbit_in(PG_FUNCTION_ARGS)
 
 /* varbit_out -
  *	  Prints the string as bits to preserve length accurately
+ *
+ * XXX varbit_recv() and hex input to varbit_in() can load a value that this
+ * cannot emit.  Consider using hex output for such values.
  */
 Datum
 varbit_out(PG_FUNCTION_ARGS)
@@ -886,6 +909,11 @@ bitcat(PG_FUNCTION_ARGS)
 	bitlen1 = VARBITLEN(arg1);
 	bitlen2 = VARBITLEN(arg2);
 
+	if (bitlen1 > VARBITMAXLEN - bitlen2)
+		ereport(ERROR,
+				(errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
+				 errmsg("bit string length exceeds the maximum allowed (%d)",
+						VARBITMAXLEN)));
 	bytelen = VARBITTOTALLEN(bitlen1 + bitlen2);
 
 	result = (VarBit *) palloc(bytelen);
diff --git a/src/include/tsearch/ts_type.h b/src/include/tsearch/ts_type.h
@@ -13,6 +13,7 @@
 #define _PG_TSTYPE_H_
 
 #include "fmgr.h"
+#include "utils/memutils.h"
 #include "utils/pg_crc.h"
 
 
@@ -242,6 +243,8 @@ typedef TSQueryData *TSQuery;
  * QueryItems, and lenofoperand is the total length of all operands
  */
 #define COMPUTESIZE(size, lenofoperand) ( HDRSIZETQ + (size) * sizeof(QueryItem) + (lenofoperand) )
+#define TSQUERY_TOO_BIG(size, lenofoperand) \
+	((size) > (MaxAllocSize - HDRSIZETQ - (lenofoperand)) / sizeof(QueryItem))
 
 /* Returns a pointer to the first QueryItem in a TSQuery */
 #define GETQUERY(x)  ((QueryItem*)( (char*)(x)+HDRSIZETQ ))
diff --git a/src/include/utils/varbit.h b/src/include/utils/varbit.h
@@ -15,6 +15,8 @@
 #ifndef VARBIT_H
 #define VARBIT_H
 
+#include <limits.h>
+
 #include "fmgr.h"
 
 /*
@@ -53,6 +55,11 @@ typedef struct
 /* Number of bytes needed to store a bit string of a given length */
 #define VARBITTOTALLEN(BITLEN)	(((BITLEN) + BITS_PER_BYTE-1)/BITS_PER_BYTE + \
 								 VARHDRSZ + VARBITHDRSZ)
+/*
+ * Maximum number of bits.  Several code sites assume no overflow from
+ * computing bitlen + X; VARBITTOTALLEN() has the largest such X.
+ */
+#define VARBITMAXLEN		(INT_MAX - BITS_PER_BYTE + 1)
 /* pointer beyond the end of the bit string (like end() in STL containers) */
 #define VARBITEND(PTR)		(((bits8 *) (PTR)) + VARSIZE(PTR))
 /* Mask that will cover exactly one byte, i.e. BITS_PER_BYTE bits */
