Fix misuse of StrNCpy to copy and add null to non-null-terminated data.

Does not work since it fetches one byte beyond the source data, and when
the phase of the moon is wrong, the source data is smack up against the
end of backend memory and you get SIGSEGV.  Don't laugh, this is a fix
for an actual user bug report.

Author: tglsfdc

contrib/miscutil/misc_utils.c

@@ -99,9 +99,9 @@ active_listeners(text *relname)
 
 	if (relname && (VARSIZE(relname) > VARHDRSZ))
 	{
+		MemSet(listen_name, 0, NAMEDATALEN);
 		len = MIN(VARSIZE(relname) - VARHDRSZ, NAMEDATALEN - 1);
-		strncpy(listen_name, VARDATA(relname), len);
-		listen_name[len] = '\0';
+		memcpy(listen_name, VARDATA(relname), len);
 		ScanKeyEntryInitialize(&key, 0,
 							   Anum_pg_listener_relname,
 							   F_NAMEEQ,

src/backend/libpq/be-fsstubs.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/libpq/be-fsstubs.c,v 1.48 2000/07/03 23:09:37 wieck Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/libpq/be-fsstubs.c,v 1.49 2000/07/07 21:12:53 tgl Exp $
  *
  * NOTES
  *	  This should be moved to a more appropriate place.  It is here
@@ -379,26 +379,23 @@ lo_import(PG_FUNCTION_ARGS)
 	/*
 	 * open the file to be read in
 	 */
-	nbytes = VARSIZE(filename) - VARHDRSZ + 1;
-	if (nbytes > FNAME_BUFSIZE)
-		nbytes = FNAME_BUFSIZE;
-	StrNCpy(fnamebuf, VARDATA(filename), nbytes);
+	nbytes = VARSIZE(filename) - VARHDRSZ;
+	if (nbytes >= FNAME_BUFSIZE)
+		nbytes = FNAME_BUFSIZE-1;
+	memcpy(fnamebuf, VARDATA(filename), nbytes);
+	fnamebuf[nbytes] = '\0';
 	fd = PathNameOpenFile(fnamebuf, O_RDONLY | PG_BINARY, 0666);
 	if (fd < 0)
-	{							/* error */
 		elog(ERROR, "lo_import: can't open unix file \"%s\": %m",
 			 fnamebuf);
-	}
 
 	/*
 	 * create an inversion "object"
 	 */
 	lobj = inv_create(INV_READ | INV_WRITE);
 	if (lobj == NULL)
-	{
 		elog(ERROR, "lo_import: can't create inv object for \"%s\"",
 			 fnamebuf);
-	}
 
 	/*
 	 * the oid for the large object is just the oid of the relation
@@ -461,18 +458,17 @@ lo_export(PG_FUNCTION_ARGS)
 	 * 022.  This code used to drop it all the way to 0, but creating
 	 * world-writable export files doesn't seem wise.
 	 */
-	nbytes = VARSIZE(filename) - VARHDRSZ + 1;
-	if (nbytes > FNAME_BUFSIZE)
-		nbytes = FNAME_BUFSIZE;
-	StrNCpy(fnamebuf, VARDATA(filename), nbytes);
+	nbytes = VARSIZE(filename) - VARHDRSZ;
+	if (nbytes >= FNAME_BUFSIZE)
+		nbytes = FNAME_BUFSIZE-1;
+	memcpy(fnamebuf, VARDATA(filename), nbytes);
+	fnamebuf[nbytes] = '\0';
 	oumask = umask((mode_t) 0022);
 	fd = PathNameOpenFile(fnamebuf, O_CREAT | O_WRONLY | O_TRUNC | PG_BINARY, 0666);
 	umask(oumask);
 	if (fd < 0)
-	{							/* error */
 		elog(ERROR, "lo_export: can't open unix file \"%s\": %m",
 			 fnamebuf);
-	}
 
 	/*
 	 * read in from the Unix file and write to the inversion file

src/backend/libpq/be-pqexec.c

@@ -9,7 +9,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/libpq/Attic/be-pqexec.c,v 1.35 2000/07/05 23:11:19 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/libpq/Attic/be-pqexec.c,v 1.36 2000/07/07 21:12:53 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -236,8 +236,8 @@ strmake(char *str, int len)
 	if (len <= 0)
 		len = strlen(str);
 
-	newstr = (char *) palloc((unsigned) len + 1);
-	StrNCpy(newstr, str, len + 1);
+	newstr = (char *) palloc(len + 1);
+	memcpy(newstr, str, len);
 	newstr[len] = (char) 0;
 	return newstr;
 }

src/backend/port/dynloader/aix.c

@@ -536,7 +536,8 @@ readExports(ModulePtr mp)
 			 * first SYMNMLEN chars and make sure we have a zero byte at
 			 * the end.
 			 */
-			StrNCpy(tmpsym, ls->l_name, SYMNMLEN + 1);
+			strncpy(tmpsym, ls->l_name, SYMNMLEN);
+			tmpsym[SYMNMLEN] = '\0';
 			symname = tmpsym;
 		}
 		ep->name = strdup(symname);

src/backend/utils/adt/like.c

@@ -11,7 +11,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	$Header: /cvsroot/pgsql/src/backend/utils/adt/like.c,v 1.36 2000/07/06 05:48:11 tgl Exp $
+ *	$Header: /cvsroot/pgsql/src/backend/utils/adt/like.c,v 1.37 2000/07/07 21:12:50 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -48,7 +48,8 @@ fixedlen_like(char *s, text *p, int charlen)
 	(void) pg_mb2wchar_with_len((unsigned char *) s, sterm, charlen);
 #else
 	sterm = (char *) palloc(charlen + 1);
-	StrNCpy(sterm, s, charlen + 1);
+	memcpy(sterm, s, charlen);
+	sterm[charlen] = '\0';
 #endif
 
 	/*

src/backend/utils/adt/not_in.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/utils/adt/Attic/not_in.c,v 1.23 2000/06/09 01:11:09 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/utils/adt/Attic/not_in.c,v 1.24 2000/07/07 21:12:50 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -52,10 +52,12 @@ int4notin(PG_FUNCTION_ARGS)
 	char		my_copy[NAMEDATALEN * 2 + 2];
 	Datum		value;
 
-	strlength = VARSIZE(relation_and_attr) - VARHDRSZ + 1;
-	if (strlength > sizeof(my_copy))
-		strlength = sizeof(my_copy);
-	StrNCpy(my_copy, VARDATA(relation_and_attr), strlength);
+	/* make a null-terminated copy of text */
+	strlength = VARSIZE(relation_and_attr) - VARHDRSZ;
+	if (strlength >= sizeof(my_copy))
+		strlength = sizeof(my_copy)-1;
+	memcpy(my_copy, VARDATA(relation_and_attr), strlength);
+	my_copy[strlength] = '\0';
 
 	relation = (char *) strtok(my_copy, ".");
 	attribute = (char *) strtok(NULL, ".");

src/backend/utils/adt/regexp.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/utils/adt/regexp.c,v 1.32 2000/07/06 05:48:11 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/utils/adt/regexp.c,v 1.33 2000/07/07 21:12:50 tgl Exp $
  *
  *		Alistair Crooks added the code for the regex caching
  *		agc - cached the regular expressions used - there's a good chance
@@ -164,7 +164,8 @@ fixedlen_regexeq(char *s, text *p, int charlen, int cflags)
 
 	/* be sure sterm is null-terminated */
 	sterm = (char *) palloc(charlen + 1);
-	StrNCpy(sterm, s, charlen + 1);
+	memcpy(sterm, s, charlen);
+	sterm[charlen] = '\0';
 
 	result = RE_compile_and_execute(p, sterm, cflags);
 

src/backend/utils/adt/varchar.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/utils/adt/varchar.c,v 1.67 2000/07/03 23:09:53 wieck Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/utils/adt/varchar.c,v 1.68 2000/07/07 21:12:50 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -115,9 +115,11 @@ bpcharout(PG_FUNCTION_ARGS)
 	char	   *result;
 	int			len;
 
+	/* copy and add null term */
 	len = VARSIZE(s) - VARHDRSZ;
 	result = (char *) palloc(len + 1);
-	StrNCpy(result, VARDATA(s), len + 1); /* copy and add null term */
+	memcpy(result, VARDATA(s), len);
+	result[len] = '\0';
 
 #ifdef CYR_RECODE
 	convertstr(result, len, 1);
@@ -268,8 +270,8 @@ bpchar_name(char *s)
 		return NULL;
 
 	len = VARSIZE(s) - VARHDRSZ;
-	if (len > NAMEDATALEN)
-		len = NAMEDATALEN;
+	if (len >= NAMEDATALEN)
+		len = NAMEDATALEN-1;
 
 	while (len > 0)
 	{
@@ -284,7 +286,7 @@ bpchar_name(char *s)
 #endif
 
 	result = (NameData *) palloc(NAMEDATALEN);
-	StrNCpy(NameStr(*result), VARDATA(s), NAMEDATALEN);
+	memcpy(NameStr(*result), VARDATA(s), len);
 
 	/* now null pad to full length... */
 	while (len < NAMEDATALEN)
@@ -316,7 +318,7 @@ name_bpchar(NameData *s)
 #endif
 
 	result = (char *) palloc(VARHDRSZ + len);
-	strncpy(VARDATA(result), NameStr(*s), len);
+	memcpy(VARDATA(result), NameStr(*s), len);
 	VARATT_SIZEP(result) = len + VARHDRSZ;
 
 	return result;
@@ -365,9 +367,11 @@ varcharout(PG_FUNCTION_ARGS)
 	char	   *result;
 	int			len;
 
+	/* copy and add null term */
 	len = VARSIZE(s) - VARHDRSZ;
 	result = (char *) palloc(len + 1);
-	StrNCpy(result, VARDATA(s), len + 1); /* copy and add null term */
+	memcpy(result, VARDATA(s), len);
+	result[len] = '\0';
 
 #ifdef CYR_RECODE
 	convertstr(result, len, 1);

src/include/c.h

@@ -8,7 +8,7 @@
  * Portions Copyright (c) 1996-2000, PostgreSQL, Inc
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $Id: c.h,v 1.75 2000/07/06 21:33:44 petere Exp $
+ * $Id: c.h,v 1.76 2000/07/07 21:12:47 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -781,11 +781,19 @@ extern int	assertTest(int val);
 
 /*
  * StrNCpy
- *		Like standard library function strncpy(), except that result string
- *		is guaranteed to be null-terminated --- that is, at most N-1 bytes
- *		of the source string will be kept.
- *		Also, the macro returns no result (too hard to do that without
- *		evaluating the arguments multiple times, which seems worse).
+ *	Like standard library function strncpy(), except that result string
+ *	is guaranteed to be null-terminated --- that is, at most N-1 bytes
+ *	of the source string will be kept.
+ *	Also, the macro returns no result (too hard to do that without
+ *	evaluating the arguments multiple times, which seems worse).
+ *
+ *	BTW: when you need to copy a non-null-terminated string (like a text
+ *	datum) and add a null, do not do it with StrNCpy(..., len+1).  That
+ *	might seem to work, but it fetches one byte more than there is in the
+ *	text object.  One fine day you'll have a SIGSEGV because there isn't
+ *	another byte before the end of memory.  Don't laugh, we've had real
+ *	live bug reports from real live users over exactly this mistake.
+ *	Do it honestly with "memcpy(dst,src,len); dst[len] = '\0';", instead.
  */
 #define StrNCpy(dst,src,len) \
 	do \