1 /* 2 * Copyright (C) 2016 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 #include <assert.h> 18 #include <stdint.h> 19 #include <string.h> 20 21 #include "expat.h" 22 #include "siphash.h" 23 24 // Macros to convert preprocessor macros to string literals. See 25 // https://gcc.gnu.org/onlinedocs/gcc-3.4.3/cpp/Stringification.html 26 #define xstr(s) str(s) 27 #define str(s) #s 28 29 // The encoder type that we wish to fuzz should come from the compile-time 30 // definition `ENCODING_FOR_FUZZING`. This allows us to have a separate fuzzer 31 // binary for 32 #ifndef ENCODING_FOR_FUZZING 33 # error "ENCODING_FOR_FUZZING was not provided to this fuzz target." 34 #endif 35 36 // 16-byte deterministic hash key. 37 static unsigned char hash_key[16] = "FUZZING IS FUN!"; 38 39 static void XMLCALL 40 start(void *userData, const XML_Char *name, const XML_Char **atts) { 41 (void)userData; 42 (void)name; 43 (void)atts; 44 } 45 static void XMLCALL 46 end(void *userData, const XML_Char *name) { 47 (void)userData; 48 (void)name; 49 } 50 51 int 52 LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) { 53 if (size == 0) 54 return 0; 55 56 XML_Parser p = XML_ParserCreate(xstr(ENCODING_FOR_FUZZING)); 57 assert(p); 58 XML_SetElementHandler(p, start, end); 59 60 // Set the hash salt using siphash to generate a deterministic hash. 61 struct sipkey *key = sip_keyof(hash_key); 62 XML_SetHashSalt(p, (unsigned long)siphash24(data, size, key)); 63 64 void *buf = XML_GetBuffer(p, size); 65 assert(buf); 66 67 memcpy(buf, data, size); 68 XML_ParseBuffer(p, size, size == 0); 69 XML_ParserFree(p); 70 return 0; 71 } 72