postgres.git / summary / log / commit / refs

commit    49bca9ea53f6428f7ac6372ad4dd47ecacfac395
Author:   Tom Lane <tgl@sss.pgh.pa.us>
Date:     Tue Jul 01 15:22:46 2014 +0000

    Fix inadequately-sized output buffer in contrib/unaccent.
    
    The output buffer size in unaccent_lexize() was calculated as input string
    length times pg_database_encoding_max_length(), which effectively assumes
    that replacement strings aren't more than one character.  While that was
    all that we previously documented it to support, the code actually has
    always allowed replacement strings of arbitrary length; so if you tried
    to make use of longer strings, you were at risk of buffer overrun.  To fix,
    use an expansible StringInfo buffer instead of trying to determine the
    maximum space needed a-priori.
    
    This would be a security issue if unaccent rules files could be installed
    by unprivileged users; but fortunately they can't, so in the back branches
    the problem can be labeled as improper configuration by a superuser.
    Nonetheless, a memory stomp isn't a nice way of reacting to improper
    configuration, so let's back-patch the fix.


 contrib/unaccent/unaccent.c | 51 ++++++++++++++++++++++++---------------------
 1 file changed, 27 insertions(+), 24 deletions(-)

diff --git a/contrib/unaccent/unaccent.c b/contrib/unaccent/unaccent.c
index a337df61af4..f2dc76bf169 100644
--- a/contrib/unaccent/unaccent.c
+++ b/contrib/unaccent/unaccent.c
@@ -15,6 +15,7 @@
 
 #include "catalog/namespace.h"
 #include "commands/defrem.h"
+#include "lib/stringinfo.h"
 #include "tsearch/ts_cache.h"
 #include "tsearch/ts_locale.h"
 #include "tsearch/ts_public.h"
@@ -263,46 +264,48 @@ unaccent_lexize(PG_FUNCTION_ARGS)
 	TrieChar   *rootTrie = (TrieChar *) PG_GETARG_POINTER(0);
 	char	   *srcchar = (char *) PG_GETARG_POINTER(1);
 	int32		len = PG_GETARG_INT32(2);
-	char	   *srcstart,
-			   *trgchar = NULL;
-	int			charlen;
-	TSLexeme   *res = NULL;
-	TrieChar   *node;
+	char	   *srcstart = srcchar;
+	TSLexeme   *res;
+	StringInfoData buf;
+
+	/* we allocate storage for the buffer only if needed */
+	buf.data = NULL;
 
-	srcstart = srcchar;
 	while (srcchar - srcstart < len)
 	{
+		TrieChar   *node;
+		int			charlen;
+
 		charlen = pg_mblen(srcchar);
 
 		node = findReplaceTo(rootTrie, (unsigned char *) srcchar, charlen);
 		if (node && node->replaceTo)
 		{
-			if (!res)
+			if (buf.data == NULL)
 			{
-				/* allocate res only if it's needed */
-				res = palloc0(sizeof(TSLexeme) * 2);
-				res->lexeme = trgchar = palloc(len * pg_database_encoding_max_length() + 1 /* \0 */ );
-				res->flags = TSL_FILTER;
+				/* initialize buffer */
+				initStringInfo(&buf);
+				/* insert any data we already skipped over */
 				if (srcchar != srcstart)
-				{
-					memcpy(trgchar, srcstart, srcchar - srcstart);
-					trgchar += (srcchar - srcstart);
-				}
+					appendBinaryStringInfo(&buf, srcstart, srcchar - srcstart);
 			}
-			memcpy(trgchar, node->replaceTo, node->replacelen);
-			trgchar += node->replacelen;
-		}
-		else if (res)
-		{
-			memcpy(trgchar, srcchar, charlen);
-			trgchar += charlen;
+			appendBinaryStringInfo(&buf, node->replaceTo, node->replacelen);
 		}
+		else if (buf.data != NULL)
+			appendBinaryStringInfo(&buf, srcchar, charlen);
 
 		srcchar += charlen;
 	}
 
-	if (res)
-		*trgchar = '\0';
+	/* return a result only if we made at least one substitution */
+	if (buf.data != NULL)
+	{
+		res = (TSLexeme *) palloc0(sizeof(TSLexeme) * 2);
+		res->lexeme = buf.data;
+		res->flags = TSL_FILTER;
+	}
+	else
+		res = NULL;
 
 	PG_RETURN_POINTER(res);
 }


[parent: 4dc3df9d1938]