Fix a passel of ancient bugs in to_char(), including two distinct buffer

overruns (neither of which seem likely to be exploitable as security holes,
fortunately, since the provoker can't control the data written).  One of
these is due to choosing to stomp on the output of a called function, which
is bad news in any case; make it treat the called functions' results as
read-only.  Avoid some unnecessary palloc/pfree traffic too; it's not
really helpful to free small temporary objects, and again this is presuming
more than it ought to about the nature of the results of called functions.
Per report from Patrick Welche and additional code-reading by Imad.

Author: tglsfdc

src/backend/utils/adt/formatting.c

@@ -1,7 +1,7 @@
 /* -----------------------------------------------------------------------
  * formatting.c
  *
- * $PostgreSQL: pgsql/src/backend/utils/adt/formatting.c,v 1.129 2007/02/27 23:48:08 tgl Exp $
+ * $PostgreSQL: pgsql/src/backend/utils/adt/formatting.c,v 1.130 2007/06/29 01:51:35 tgl Exp $
  *
  *
  *	 Portions Copyright (c) 1999-2007, PostgreSQL Global Development Group
@@ -74,6 +74,7 @@
 #include <unistd.h>
 #include <math.h>
 #include <float.h>
+#include <limits.h>
 #include <locale.h>
 
 #include "utils/builtins.h"
@@ -112,8 +113,8 @@
  * More is in float.c
  * ----------
  */
-#define MAXFLOATWIDTH	64
-#define MAXDOUBLEWIDTH	128
+#define MAXFLOATWIDTH	60
+#define MAXDOUBLEWIDTH	500
 
 
 /* ----------
@@ -958,13 +959,12 @@ static char *localize_month(int index);
 static char *localize_day_full(int index);
 static char *localize_day(int index);
 
-/*
- * External (defined in oracle_compat.c 
- */
 #if defined(HAVE_WCSTOMBS) && defined(HAVE_TOWLOWER)
 #define USE_WIDE_UPPER_LOWER
+/* externs are in oracle_compat.c */
 extern char *wstring_upper(char *str);
 extern char *wstring_lower(char *str);
+
 static char *localized_str_toupper(char *buff);
 static char *localized_str_tolower(char *buff);
 #else
@@ -1510,7 +1510,7 @@ str_numth(char *dest, char *num, int type)
 }
 
 /* ----------
- * Convert string to upper-string. Input string is modified in place.
+ * Convert string to upper case. Input string is modified in place.
  * ----------
  */
 static char *
@@ -1531,7 +1531,7 @@ str_toupper(char *buff)
 }
 
 /* ----------
- * Convert string to lower-string. Input string is modified in place.
+ * Convert string to lower case. Input string is modified in place.
  * ----------
  */
 static char *
@@ -1553,7 +1553,8 @@ str_tolower(char *buff)
 
 #ifdef USE_WIDE_UPPER_LOWER
 /* ----------
- * Convert localized string to upper string. Input string is modified in place.
+ * Convert localized string to upper case.
+ * Input string may be modified in place ... or we might make a copy.
  * ----------
  */
 static char *
@@ -1579,7 +1580,8 @@ localized_str_toupper(char *buff)
 }
 
 /* ----------
- * Convert localized string to upper string. Input string is modified in place.
+ * Convert localized string to lower case.
+ * Input string may be modified in place ... or we might make a copy.
  * ----------
  */
 static char *
@@ -2107,19 +2109,16 @@ dch_time(int arg, char *inout, int suf, bool is_to_char, bool is_interval,
 			INVALID_FOR_INTERVAL;
 			if (is_to_char && tmtcTzn(tmtc))
 			{
-				int			siz = strlen(tmtcTzn(tmtc));
-
 				if (arg == DCH_TZ)
 					strcpy(inout, tmtcTzn(tmtc));
 				else
 				{
-					char	   *p = palloc(siz);
+					char	   *p = pstrdup(tmtcTzn(tmtc));
 
-					strcpy(p, tmtcTzn(tmtc));
 					strcpy(inout, str_tolower(p));
 					pfree(p);
 				}
-				return siz;
+				return strlen(inout);
 			}
 			else if (!is_to_char)
 				ereport(ERROR,
@@ -3624,7 +3623,7 @@ static char *
 fill_str(char *str, int c, int max)
 {
 	memset(str, c, max);
-	*(str + max + 1) = '\0';
+	*(str + max) = '\0';
 	return str;
 }
 
@@ -4798,10 +4797,9 @@ NUM_processor(FormatNode *node, NUMDesc *Num, char *inout, char *number,
 #define NUM_TOCHAR_prepare \
 do { \
 	len = VARSIZE(fmt) - VARHDRSZ;					\
-	if (len <= 0)							\
+	if (len <= 0 || len >= (INT_MAX-VARHDRSZ)/NUM_MAX_ITEM_SIZ)		\
 		return DirectFunctionCall1(textin, CStringGetDatum(""));	\
-	result	= (text *) palloc( (len * NUM_MAX_ITEM_SIZ) + 1 + VARHDRSZ); \
-	memset(result, 0,  (len * NUM_MAX_ITEM_SIZ) + 1 + VARHDRSZ ); \
+	result	= (text *) palloc0((len * NUM_MAX_ITEM_SIZ) + 1 + VARHDRSZ);	\
 	format	= NUM_cache(len, &Num, VARDATA(fmt), &shouldFree);		\
 } while (0)
 
@@ -4811,30 +4809,19 @@ do { \
  */
 #define NUM_TOCHAR_finish \
 do { \
-	NUM_processor(format, &Num, VARDATA(result),			\
-		numstr, plen, sign, true);				\
-	pfree(orgnum);							\
+	NUM_processor(format, &Num, VARDATA(result), numstr, plen, sign, true);	\
 									\
-	if (shouldFree)							\
-		pfree(format);						\
+	if (shouldFree)					\
+		pfree(format);				\
 									\
-	/*
-	 * for result is allocated max memory, which current format-picture\
-	 * needs, now it must be re-allocate to result real size	\
+	/*								\
+	 * Convert null-terminated representation of result to standard text. \
+	 * The result is usually much bigger than it needs to be, but there \
+	 * seems little point in realloc'ing it smaller. \
 	 */								\
-	if (!(len = strlen(VARDATA(result))))				\
-	{								\
-		pfree(result);						\
-		PG_RETURN_NULL();					\
-	}								\
-									\
-	result_tmp	= result;					\
-	result		= (text *) palloc(len + VARHDRSZ);		\
-									\
-	memcpy(VARDATA(result), VARDATA(result_tmp), len);	\
-	SET_VARSIZE(result, len + VARHDRSZ);				\
-	pfree(result_tmp);						\
-} while(0)
+	len = strlen(VARDATA(result));	\
+	SET_VARSIZE(result, len + VARHDRSZ); \
+} while (0)
 
 /* -------------------
  * NUMERIC to_number() (convert string to numeric)
@@ -4856,7 +4843,7 @@ numeric_to_number(PG_FUNCTION_ARGS)
 
 	len = VARSIZE(fmt) - VARHDRSZ;
 
-	if (len <= 0)
+	if (len <= 0 || len >= INT_MAX/NUM_MAX_ITEM_SIZ)
 		PG_RETURN_NULL();
 
 	format = NUM_cache(len, &Num, VARDATA(fmt), &shouldFree);
@@ -4891,8 +4878,7 @@ numeric_to_char(PG_FUNCTION_ARGS)
 	text	   *fmt = PG_GETARG_TEXT_P(1);
 	NUMDesc		Num;
 	FormatNode *format;
-	text	   *result,
-			   *result_tmp;
+	text	   *result;
 	bool		shouldFree;
 	int			len = 0,
 				plen = 0,
@@ -4915,7 +4901,6 @@ numeric_to_char(PG_FUNCTION_ARGS)
 		numstr = orgnum =
 			int_to_roman(DatumGetInt32(DirectFunctionCall1(numeric_int4,
 													   NumericGetDatum(x))));
-		pfree(x);
 	}
 	else
 	{
@@ -4934,9 +4919,6 @@ numeric_to_char(PG_FUNCTION_ARGS)
 			val = DatumGetNumeric(DirectFunctionCall2(numeric_mul,
 													  NumericGetDatum(value),
 													  NumericGetDatum(x)));
-			pfree(x);
-			pfree(a);
-			pfree(b);
 			Num.pre += Num.multi;
 		}
 
@@ -4945,10 +4927,9 @@ numeric_to_char(PG_FUNCTION_ARGS)
 												Int32GetDatum(Num.post)));
 		orgnum = DatumGetCString(DirectFunctionCall1(numeric_out,
 													 NumericGetDatum(x)));
-		pfree(x);
 
 		if (*orgnum == '-')
-		{						/* < 0 */
+		{
 			sign = '-';
 			numstr = orgnum + 1;
 		}
@@ -4966,13 +4947,10 @@ numeric_to_char(PG_FUNCTION_ARGS)
 			plen = Num.pre - len;
 		else if (len > Num.pre)
 		{
-			fill_str(numstr, '#', Num.pre);
+			numstr = (char *) palloc(Num.pre + Num.post + 2);
+			fill_str(numstr, '#', Num.pre + Num.post + 1);
 			*(numstr + Num.pre) = '.';
-			fill_str(numstr + 1 + Num.pre, '#', Num.post);
 		}
-
-		if (IS_MULTI(&Num))
-			pfree(val);
 	}
 
 	NUM_TOCHAR_finish;
@@ -4990,8 +4968,7 @@ int4_to_char(PG_FUNCTION_ARGS)
 	text	   *fmt = PG_GETARG_TEXT_P(1);
 	NUMDesc		Num;
 	FormatNode *format;
-	text	   *result,
-			   *result_tmp;
+	text	   *result;
 	bool		shouldFree;
 	int			len = 0,
 				plen = 0,
@@ -5019,40 +4996,34 @@ int4_to_char(PG_FUNCTION_ARGS)
 			orgnum = DatumGetCString(DirectFunctionCall1(int4out,
 													  Int32GetDatum(value)));
 		}
-		len = strlen(orgnum);
 
 		if (*orgnum == '-')
-		{						/* < 0 */
+		{
 			sign = '-';
-			--len;
+			orgnum++;
 		}
 		else
 			sign = '+';
+		len = strlen(orgnum);
 
 		if (Num.post)
 		{
-			int			i;
-
 			numstr = (char *) palloc(len + Num.post + 2);
-			strcpy(numstr, orgnum + (*orgnum == '-' ? 1 : 0));
+			strcpy(numstr, orgnum);
 			*(numstr + len) = '.';
-
-			for (i = len + 1; i <= len + Num.post; i++)
-				*(numstr + i) = '0';
+			memset(numstr + len + 1, '0', Num.post);
 			*(numstr + len + Num.post + 1) = '\0';
-			pfree(orgnum);
-			orgnum = numstr;
 		}
 		else
-			numstr = orgnum + (*orgnum == '-' ? 1 : 0);
+			numstr = orgnum;
 
 		if (Num.pre > len)
 			plen = Num.pre - len;
 		else if (len > Num.pre)
 		{
-			fill_str(numstr, '#', Num.pre);
+			numstr = (char *) palloc(Num.pre + Num.post + 2);
+			fill_str(numstr, '#', Num.pre + Num.post + 1);
 			*(numstr + Num.pre) = '.';
-			fill_str(numstr + 1 + Num.pre, '#', Num.post);
 		}
 	}
 
@@ -5071,8 +5042,7 @@ int8_to_char(PG_FUNCTION_ARGS)
 	text	   *fmt = PG_GETARG_TEXT_P(1);
 	NUMDesc		Num;
 	FormatNode *format;
-	text	   *result,
-			   *result_tmp;
+	text	   *result;
 	bool		shouldFree;
 	int			len = 0,
 				plen = 0,
@@ -5106,40 +5076,34 @@ int8_to_char(PG_FUNCTION_ARGS)
 
 		orgnum = DatumGetCString(DirectFunctionCall1(int8out,
 													 Int64GetDatum(value)));
-		len = strlen(orgnum);
 
 		if (*orgnum == '-')
-		{						/* < 0 */
+		{
 			sign = '-';
-			--len;
+			orgnum++;
 		}
 		else
 			sign = '+';
+		len = strlen(orgnum);
 
 		if (Num.post)
 		{
-			int			i;
-
 			numstr = (char *) palloc(len + Num.post + 2);
-			strcpy(numstr, orgnum + (*orgnum == '-' ? 1 : 0));
+			strcpy(numstr, orgnum);
 			*(numstr + len) = '.';
-
-			for (i = len + 1; i <= len + Num.post; i++)
-				*(numstr + i) = '0';
+			memset(numstr + len + 1, '0', Num.post);
 			*(numstr + len + Num.post + 1) = '\0';
-			pfree(orgnum);
-			orgnum = numstr;
 		}
 		else
-			numstr = orgnum + (*orgnum == '-' ? 1 : 0);
+			numstr = orgnum;
 
 		if (Num.pre > len)
 			plen = Num.pre - len;
 		else if (len > Num.pre)
 		{
-			fill_str(numstr, '#', Num.pre);
+			numstr = (char *) palloc(Num.pre + Num.post + 2);
+			fill_str(numstr, '#', Num.pre + Num.post + 1);
 			*(numstr + Num.pre) = '.';
-			fill_str(numstr + 1 + Num.pre, '#', Num.post);
 		}
 	}
 
@@ -5158,8 +5122,7 @@ float4_to_char(PG_FUNCTION_ARGS)
 	text	   *fmt = PG_GETARG_TEXT_P(1);
 	NUMDesc		Num;
 	FormatNode *format;
-	text	   *result,
-			   *result_tmp;
+	text	   *result;
 	bool		shouldFree;
 	int			len = 0,
 				plen = 0,
@@ -5214,9 +5177,9 @@ float4_to_char(PG_FUNCTION_ARGS)
 			plen = Num.pre - len;
 		else if (len > Num.pre)
 		{
-			fill_str(numstr, '#', Num.pre);
+			numstr = (char *) palloc(Num.pre + Num.post + 2);
+			fill_str(numstr, '#', Num.pre + Num.post + 1);
 			*(numstr + Num.pre) = '.';
-			fill_str(numstr + 1 + Num.pre, '#', Num.post);
 		}
 	}
 
@@ -5235,8 +5198,7 @@ float8_to_char(PG_FUNCTION_ARGS)
 	text	   *fmt = PG_GETARG_TEXT_P(1);
 	NUMDesc		Num;
 	FormatNode *format;
-	text	   *result,
-			   *result_tmp;
+	text	   *result;
 	bool		shouldFree;
 	int			len = 0,
 				plen = 0,
@@ -5289,9 +5251,9 @@ float8_to_char(PG_FUNCTION_ARGS)
 			plen = Num.pre - len;
 		else if (len > Num.pre)
 		{
-			fill_str(numstr, '#', Num.pre);
+			numstr = (char *) palloc(Num.pre + Num.post + 2);
+			fill_str(numstr, '#', Num.pre + Num.post + 1);
 			*(numstr + Num.pre) = '.';
-			fill_str(numstr + 1 + Num.pre, '#', Num.post);
 		}
 	}