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Commit59e6116

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Fix inadequately-sized output buffer in contrib/unaccent.
The output buffer size in unaccent_lexize() was calculated as input stringlength times pg_database_encoding_max_length(), which effectively assumesthat replacement strings aren't more than one character. While that wasall that we previously documented it to support, the code actually hasalways allowed replacement strings of arbitrary length; so if you triedto make use of longer strings, you were at risk of buffer overrun. To fix,use an expansible StringInfo buffer instead of trying to determine themaximum space needed a-priori.This would be a security issue if unaccent rules files could be installedby unprivileged users; but fortunately they can't, so in the back branchesthe problem can be labeled as improper configuration by a superuser.Nonetheless, a memory stomp isn't a nice way of reacting to improperconfiguration, so let's back-patch the fix.
1 parentf14e408 commit59e6116

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+27
-24
lines changed

1 file changed

+27
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‎contrib/unaccent/unaccent.c

Lines changed: 27 additions & 24 deletions
Original file line numberDiff line numberDiff line change
@@ -15,6 +15,7 @@
1515

1616
#include"catalog/namespace.h"
1717
#include"commands/defrem.h"
18+
#include"lib/stringinfo.h"
1819
#include"tsearch/ts_cache.h"
1920
#include"tsearch/ts_locale.h"
2021
#include"tsearch/ts_public.h"
@@ -265,46 +266,48 @@ unaccent_lexize(PG_FUNCTION_ARGS)
265266
TrieChar*rootTrie= (TrieChar*)PG_GETARG_POINTER(0);
266267
char*srcchar= (char*)PG_GETARG_POINTER(1);
267268
int32len=PG_GETARG_INT32(2);
268-
char*srcstart,
269-
*trgchar=NULL;
270-
intcharlen;
271-
TSLexeme*res=NULL;
272-
TrieChar*node;
269+
char*srcstart=srcchar;
270+
TSLexeme*res;
271+
StringInfoDatabuf;
272+
273+
/* we allocate storage for the buffer only if needed */
274+
buf.data=NULL;
273275

274-
srcstart=srcchar;
275276
while (srcchar-srcstart<len)
276277
{
278+
TrieChar*node;
279+
intcharlen;
280+
277281
charlen=pg_mblen(srcchar);
278282

279283
node=findReplaceTo(rootTrie, (unsignedchar*)srcchar,charlen);
280284
if (node&&node->replaceTo)
281285
{
282-
if (!res)
286+
if (buf.data==NULL)
283287
{
284-
/* allocate res only if it's needed */
285-
res=palloc0(sizeof(TSLexeme)*2);
286-
res->lexeme=trgchar=palloc(len*pg_database_encoding_max_length()+1/* \0 */ );
287-
res->flags=TSL_FILTER;
288+
/* initialize buffer */
289+
initStringInfo(&buf);
290+
/* insert any data we already skipped over */
288291
if (srcchar!=srcstart)
289-
{
290-
memcpy(trgchar,srcstart,srcchar-srcstart);
291-
trgchar+= (srcchar-srcstart);
292-
}
292+
appendBinaryStringInfo(&buf,srcstart,srcchar-srcstart);
293293
}
294-
memcpy(trgchar,node->replaceTo,node->replacelen);
295-
trgchar+=node->replacelen;
296-
}
297-
elseif (res)
298-
{
299-
memcpy(trgchar,srcchar,charlen);
300-
trgchar+=charlen;
294+
appendBinaryStringInfo(&buf,node->replaceTo,node->replacelen);
301295
}
296+
elseif (buf.data!=NULL)
297+
appendBinaryStringInfo(&buf,srcchar,charlen);
302298

303299
srcchar+=charlen;
304300
}
305301

306-
if (res)
307-
*trgchar='\0';
302+
/* return a result only if we made at least one substitution */
303+
if (buf.data!=NULL)
304+
{
305+
res= (TSLexeme*)palloc0(sizeof(TSLexeme)*2);
306+
res->lexeme=buf.data;
307+
res->flags=TSL_FILTER;
308+
}
309+
else
310+
res=NULL;
308311

309312
PG_RETURN_POINTER(res);
310313
}

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