res_config_sqlite3: Fix crashes when reading peers from sqlite3 tables

Introduced realloaction of ast_str buf in sqlite3_escape functions in case
the returned buffer from threadstorage was actually too small.

Change-Id: I3c5eb43aaade93ee457943daddc651781954c445

res/res_config_sqlite3.c

@@ -127,8 +127,14 @@ static inline const char *sqlite3_escape_string_helper(struct ast_threadstorage
 	 * add two quotes, and convert NULL pointers to the word "NULL", but we
 	 * don't allow those anyway. Just going to use %q for now. */
 	struct ast_str *buf = ast_str_thread_get(ts, maxlen);
-	char *tmp = ast_str_buffer(buf);
 	char q = ts == &escape_value_buf ? '\'' : '"';
+	char *tmp;
+
+	if (ast_str_size(buf) < maxlen) {
+		/* realloc if buf is too small */
+		ast_str_make_space(&buf, maxlen);
+	}
+	tmp = ast_str_buffer(buf);
 
 	ast_str_reset(buf);
 	*tmp++ = q; /* Initial quote */
@@ -160,9 +166,15 @@ static const char *sqlite3_escape_column_op(const char *param)
 {
 	size_t maxlen = strlen(param) * 2 + sizeof("\"\" =");
 	struct ast_str *buf = ast_str_thread_get(&escape_column_buf, maxlen);
-	char *tmp = ast_str_buffer(buf);
+	char *tmp;
 	int space = 0;
 
+	if (ast_str_size(buf) < maxlen) {
+		/* realloc if buf is too small */
+		ast_str_make_space(&buf, maxlen);
+	}
+	tmp = ast_str_buffer(buf);
+
 	ast_str_reset(buf);
 	*tmp++ = '"';
 	while ((*tmp++ = *param++)) {