kc3-lang/libxml2/fuzz/xpath.c
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Hash : c6c6d8af
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Date : 2024-12-11T16:24:23
fuzz: Mutate fuzz data chunks separately Implement a custom mutator that takes a list of fixed-size chunks which are mutated with a given probability. This makes sure that values like parser options or failure position are mutated regularly even as the fuzz data grows large. Values can also be adjusted temporarily to make the fuzzer focus on failure injection, for example. Thanks to David Kilzer for the idea.
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fuzz/xpath.c
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/* * xpath.c: a libFuzzer target to test XPath and XPointer expressions. * * See Copyright for the status of this software. */ #include <libxml/catalog.h> #include <libxml/parser.h> #include <libxml/xpointer.h> #include "fuzz.h" int LLVMFuzzerInitialize(int *argc ATTRIBUTE_UNUSED, char ***argv ATTRIBUTE_UNUSED) { xmlFuzzMemSetup(); xmlInitParser(); #ifdef LIBXML_CATALOG_ENABLED xmlInitializeCatalog(); xmlCatalogSetDefaults(XML_CATA_ALLOW_NONE); #endif xmlSetGenericErrorFunc(NULL, xmlFuzzErrorFunc); return 0; } int LLVMFuzzerTestOneInput(const char *data, size_t size) { xmlDocPtr doc; const char *expr, *xml; size_t failurePos, exprSize, xmlSize; if (size > 10000) return(0); xmlFuzzDataInit(data, size); failurePos = xmlFuzzReadInt(4) % (size + 100); expr = xmlFuzzReadString(&exprSize); xml = xmlFuzzReadString(&xmlSize); /* Recovery mode allows more input to be fuzzed. */ doc = xmlReadMemory(xml, xmlSize, NULL, NULL, XML_PARSE_RECOVER); if (doc != NULL) { xmlXPathContextPtr xpctxt; xmlFuzzInjectFailure(failurePos); xpctxt = xmlXPathNewContext(doc); if (xpctxt != NULL) { int res; /* Operation limit to avoid timeout */ xpctxt->opLimit = 500000; res = xmlXPathContextSetCache(xpctxt, 1, 4, 0); xmlFuzzCheckFailureReport("xmlXPathContextSetCache", res == -1, 0); xmlFuzzResetFailure(); xmlXPathFreeObject(xmlXPtrEval(BAD_CAST expr, xpctxt)); xmlFuzzCheckFailureReport("xmlXPtrEval", xpctxt->lastError.code == XML_ERR_NO_MEMORY, 0); xmlXPathFreeContext(xpctxt); } xmlFuzzInjectFailure(0); xmlFreeDoc(doc); } xmlFuzzDataCleanup(); xmlResetLastError(); return(0); } size_t LLVMFuzzerCustomMutator(char *data, size_t size, size_t maxSize, unsigned seed) { static const xmlFuzzChunkDesc chunks[] = { { 4, XML_FUZZ_PROB_ONE / 10 }, /* failurePos */ { 0, 0 } }; return xmlFuzzMutateChunks(chunks, data, size, maxSize, seed, LLVMFuzzerMutate); }