1 files changed, 105 insertions, 0 deletions
diff --git a/contrib/expat/fuzz/xml_parse_fuzzer.c b/contrib/expat/fuzz/xml_parse_fuzzer.c
new file mode 100644
index 000000000000..a7e8414ce355
--- /dev/null
+++ b/contrib/expat/fuzz/xml_parse_fuzzer.c
@@ -0,0 +1,105 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <assert.h>
+#include <stdint.h>
+
+#include "expat.h"
+#include "siphash.h"
+
+// Macros to convert preprocessor macros to string literals. See
+// https://gcc.gnu.org/onlinedocs/gcc-3.4.3/cpp/Stringification.html
+#define xstr(s) str(s)
+#define str(s) #s
+
+// The encoder type that we wish to fuzz should come from the compile-time
+// definition `ENCODING_FOR_FUZZING`. This allows us to have a separate fuzzer
+// binary for
+#ifndef ENCODING_FOR_FUZZING
+#  error "ENCODING_FOR_FUZZING was not provided to this fuzz target."
+#endif
+
+// 16-byte deterministic hash key.
+static unsigned char hash_key[16] = "FUZZING IS FUN!";
+
+static void XMLCALL
+start(void *userData, const XML_Char *name, const XML_Char **atts) {
+  (void)userData;
+  (void)name;
+  (void)atts;
+}
+static void XMLCALL
+end(void *userData, const XML_Char *name) {
+  (void)userData;
+  (void)name;
+}
+
+static void XMLCALL
+may_stop_character_handler(void *userData, const XML_Char *s, int len) {
+  XML_Parser parser = (XML_Parser)userData;
+  if (len > 1 && s[0] == 's') {
+    XML_StopParser(parser, s[1] == 'r' ? XML_FALSE : XML_TRUE);
+  }
+}
+
+static void
+ParseOneInput(XML_Parser p, const uint8_t *data, size_t size) {
+  // Set the hash salt using siphash to generate a deterministic hash.
+  struct sipkey *key = sip_keyof(hash_key);
+  XML_SetHashSalt(p, (unsigned long)siphash24(data, size, key));
+  (void)sip24_valid;
+
+  XML_SetUserData(p, p);
+  XML_SetElementHandler(p, start, end);
+  XML_SetCharacterDataHandler(p, may_stop_character_handler);
+  XML_Parse(p, (const XML_Char *)data, size, 0);
+  if (XML_Parse(p, (const XML_Char *)data, size, 1) == XML_STATUS_ERROR) {
+    XML_ErrorString(XML_GetErrorCode(p));
+  }
+  XML_GetCurrentLineNumber(p);
+  if (size % 2) {
+    XML_ParserReset(p, NULL);
+  }
+}
+
+int
+LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
+  XML_Parser parentParser = XML_ParserCreate(xstr(ENCODING_FOR_FUZZING));
+  assert(parentParser);
+  ParseOneInput(parentParser, data, size);
+  // not freed yet, but used later and freed then
+
+  XML_Parser namespaceParser = XML_ParserCreateNS(NULL, '!');
+  assert(namespaceParser);
+  ParseOneInput(namespaceParser, data, size);
+  XML_ParserFree(namespaceParser);
+
+  XML_Parser externalEntityParser
+      = XML_ExternalEntityParserCreate(parentParser, "e1", NULL);
+  assert(externalEntityParser);
+  ParseOneInput(externalEntityParser, data, size);
+  XML_ParserFree(externalEntityParser);
+
+  XML_Parser externalDtdParser
+      = XML_ExternalEntityParserCreate(parentParser, NULL, NULL);
+  assert(externalDtdParser);
+  ParseOneInput(externalDtdParser, data, size);
+  XML_ParserFree(externalDtdParser);
+
+  // finally frees this parser which served as parent
+  XML_ParserFree(parentParser);
+  return 0;
+}