From 5a421a47eb1fc4398f42678c09e35aa72dc7cf18 Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Tue, 1 Jul 2014 11:22:43 -0400 Subject: [PATCH] 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 | 45 ++++++++++++++++++++----------------- 1 file changed, 24 insertions(+), 21 deletions(-) diff --git a/contrib/unaccent/unaccent.c b/contrib/unaccent/unaccent.c index c7d54b205e..7c4072ed93 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" @@ -309,9 +310,12 @@ 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 = srcchar, - *trgchar = NULL; - TSLexeme *res = NULL; + char *srcstart = srcchar; + TSLexeme *res; + StringInfoData buf; + + /* we allocate storage for the buffer only if needed */ + buf.data = NULL; while (len > 0) { @@ -322,37 +326,36 @@ unaccent_lexize(PG_FUNCTION_ARGS) &matchlen); 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; + appendBinaryStringInfo(&buf, node->replaceTo, node->replacelen); } else { matchlen = pg_mblen(srcchar); - if (res) - { - memcpy(trgchar, srcchar, matchlen); - trgchar += matchlen; - } + if (buf.data != NULL) + appendBinaryStringInfo(&buf, srcchar, matchlen); } srcchar += matchlen; len -= matchlen; } - 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); }