mirror of
https://gitlab.gnome.org/GNOME/libxml2.git
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482 lines
10 KiB
C
482 lines
10 KiB
C
/*
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* fuzz.c: Common functions for fuzzing.
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*
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* See Copyright for the status of this software.
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <sys/stat.h>
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#include <libxml/hash.h>
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#include <libxml/parser.h>
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#include <libxml/parserInternals.h>
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#include <libxml/tree.h>
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#include <libxml/xmlIO.h>
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#include "fuzz.h"
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typedef struct {
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const char *data;
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size_t size;
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} xmlFuzzEntityInfo;
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/* Single static instance for now */
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static struct {
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/* Original data */
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const char *data;
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size_t size;
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/* Remaining data */
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const char *ptr;
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size_t remaining;
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/* Buffer for unescaped strings */
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char *outBuf;
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char *outPtr; /* Free space at end of buffer */
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xmlHashTablePtr entities; /* Maps URLs to xmlFuzzEntityInfos */
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/* The first entity is the main entity. */
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const char *mainUrl;
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xmlFuzzEntityInfo *mainEntity;
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} fuzzData;
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size_t fuzzNumAllocs;
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size_t fuzzMaxAllocs;
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int fuzzAllocFailed;
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/**
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* xmlFuzzErrorFunc:
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*
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* An error function that simply discards all errors.
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*/
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void
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xmlFuzzErrorFunc(void *ctx ATTRIBUTE_UNUSED, const char *msg ATTRIBUTE_UNUSED,
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...) {
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}
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/**
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* xmlFuzzSErrorFunc:
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*
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* A structured error function that simply discards all errors.
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*/
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void
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xmlFuzzSErrorFunc(void *ctx ATTRIBUTE_UNUSED,
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const xmlError *error ATTRIBUTE_UNUSED) {
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}
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/*
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* Malloc failure injection.
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*
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* To debug issues involving malloc failures, it's often helpful to set
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* MALLOC_ABORT to 1. This should provide a backtrace of the failed
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* allocation.
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*/
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#define XML_FUZZ_MALLOC_ABORT 0
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static void *
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xmlFuzzMalloc(size_t size) {
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void *ret;
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if (fuzzMaxAllocs > 0) {
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fuzzNumAllocs += 1;
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if (fuzzNumAllocs == fuzzMaxAllocs) {
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#if XML_FUZZ_MALLOC_ABORT
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abort();
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#endif
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fuzzAllocFailed = 1;
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return NULL;
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}
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}
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ret = malloc(size);
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if (ret == NULL)
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fuzzAllocFailed = 1;
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return ret;
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}
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static void *
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xmlFuzzRealloc(void *ptr, size_t size) {
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void *ret;
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if (fuzzMaxAllocs > 0) {
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fuzzNumAllocs += 1;
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if (fuzzNumAllocs == fuzzMaxAllocs) {
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#if XML_FUZZ_MALLOC_ABORT
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abort();
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#endif
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fuzzAllocFailed = 1;
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return NULL;
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}
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}
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ret = realloc(ptr, size);
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if (ret == NULL)
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fuzzAllocFailed = 1;
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return ret;
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}
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void
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xmlFuzzMemSetup(void) {
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xmlMemSetup(free, xmlFuzzMalloc, xmlFuzzRealloc, xmlMemStrdup);
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}
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void
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xmlFuzzMemSetLimit(size_t limit) {
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fuzzNumAllocs = 0;
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fuzzMaxAllocs = limit;
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fuzzAllocFailed = 0;
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}
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int
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xmlFuzzMallocFailed(void) {
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return fuzzAllocFailed;
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}
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void
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xmlFuzzResetMallocFailed(void) {
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fuzzAllocFailed = 0;
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}
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void
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xmlFuzzCheckMallocFailure(const char *func, int error) {
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if (error >= 0 && fuzzAllocFailed != error) {
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fprintf(stderr, "%s: malloc failure %s reported\n",
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func, fuzzAllocFailed ? "not" : "erroneously");
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abort();
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}
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fuzzAllocFailed = 0;
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}
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/**
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* xmlFuzzDataInit:
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*
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* Initialize fuzz data provider.
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*/
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void
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xmlFuzzDataInit(const char *data, size_t size) {
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fuzzData.data = data;
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fuzzData.size = size;
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fuzzData.ptr = data;
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fuzzData.remaining = size;
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fuzzData.outBuf = xmlMalloc(size + 1);
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fuzzData.outPtr = fuzzData.outBuf;
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fuzzData.entities = xmlHashCreate(8);
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fuzzData.mainUrl = NULL;
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fuzzData.mainEntity = NULL;
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}
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/**
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* xmlFuzzDataFree:
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*
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* Cleanup fuzz data provider.
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*/
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void
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xmlFuzzDataCleanup(void) {
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xmlFree(fuzzData.outBuf);
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xmlHashFree(fuzzData.entities, xmlHashDefaultDeallocator);
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}
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/**
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* xmlFuzzWriteInt:
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* @out: output file
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* @v: integer to write
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* @size: size of integer in bytes
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*
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* Write an integer to the fuzz data.
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*/
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void
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xmlFuzzWriteInt(FILE *out, size_t v, int size) {
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int shift;
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while (size > (int) sizeof(size_t)) {
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putc(0, out);
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size--;
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}
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shift = size * 8;
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while (shift > 0) {
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shift -= 8;
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putc((v >> shift) & 255, out);
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}
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}
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/**
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* xmlFuzzReadInt:
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* @size: size of integer in bytes
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*
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* Read an integer from the fuzz data.
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*/
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size_t
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xmlFuzzReadInt(int size) {
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size_t ret = 0;
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while ((size > 0) && (fuzzData.remaining > 0)) {
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unsigned char c = (unsigned char) *fuzzData.ptr++;
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fuzzData.remaining--;
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ret = (ret << 8) | c;
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size--;
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}
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return ret;
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}
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/**
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* xmlFuzzBytesRemaining:
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*
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* Return number of remaining bytes in fuzz data.
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*/
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size_t
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xmlFuzzBytesRemaining(void) {
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return(fuzzData.remaining);
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}
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/**
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* xmlFuzzReadRemaining:
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* @size: size of string in bytes
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*
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* Read remaining bytes from fuzz data.
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*/
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const char *
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xmlFuzzReadRemaining(size_t *size) {
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const char *ret = fuzzData.ptr;
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*size = fuzzData.remaining;
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fuzzData.ptr += fuzzData.remaining;
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fuzzData.remaining = 0;
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return(ret);
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}
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/*
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* xmlFuzzWriteString:
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* @out: output file
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* @str: string to write
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*
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* Write a random-length string to file in a format similar to
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* FuzzedDataProvider. Backslash followed by newline marks the end of the
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* string. Two backslashes are used to escape a backslash.
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*/
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void
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xmlFuzzWriteString(FILE *out, const char *str) {
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for (; *str; str++) {
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int c = (unsigned char) *str;
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putc(c, out);
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if (c == '\\')
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putc(c, out);
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}
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putc('\\', out);
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putc('\n', out);
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}
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/**
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* xmlFuzzReadString:
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* @size: size of string in bytes
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*
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* Read a random-length string from the fuzz data.
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*
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* The format is similar to libFuzzer's FuzzedDataProvider but treats
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* backslash followed by newline as end of string. This makes the fuzz data
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* more readable. A backslash character is escaped with another backslash.
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*
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* Returns a zero-terminated string or NULL if the fuzz data is exhausted.
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*/
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const char *
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xmlFuzzReadString(size_t *size) {
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const char *out = fuzzData.outPtr;
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while (fuzzData.remaining > 0) {
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int c = *fuzzData.ptr++;
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fuzzData.remaining--;
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if ((c == '\\') && (fuzzData.remaining > 0)) {
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int c2 = *fuzzData.ptr;
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if (c2 == '\n') {
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fuzzData.ptr++;
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fuzzData.remaining--;
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if (size != NULL)
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*size = fuzzData.outPtr - out;
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*fuzzData.outPtr++ = '\0';
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return(out);
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}
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if (c2 == '\\') {
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fuzzData.ptr++;
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fuzzData.remaining--;
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}
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}
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*fuzzData.outPtr++ = c;
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}
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if (fuzzData.outPtr > out) {
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if (size != NULL)
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*size = fuzzData.outPtr - out;
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*fuzzData.outPtr++ = '\0';
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return(out);
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}
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if (size != NULL)
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*size = 0;
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return(NULL);
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}
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/**
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* xmlFuzzReadEntities:
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*
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* Read entities like the main XML file, external DTDs, external parsed
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* entities from fuzz data.
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*/
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void
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xmlFuzzReadEntities(void) {
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size_t num = 0;
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while (1) {
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const char *url, *entity;
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size_t urlSize, entitySize;
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xmlFuzzEntityInfo *entityInfo;
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url = xmlFuzzReadString(&urlSize);
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if (url == NULL) break;
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entity = xmlFuzzReadString(&entitySize);
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if (entity == NULL) break;
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/*
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* Cap URL size to avoid quadratic behavior when generating
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* error messages or looking up entities.
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*/
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if (urlSize < 50 &&
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xmlHashLookup(fuzzData.entities, (xmlChar *)url) == NULL) {
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entityInfo = xmlMalloc(sizeof(xmlFuzzEntityInfo));
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if (entityInfo == NULL)
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break;
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entityInfo->data = entity;
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entityInfo->size = entitySize;
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xmlHashAddEntry(fuzzData.entities, (xmlChar *)url, entityInfo);
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if (num == 0) {
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fuzzData.mainUrl = url;
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fuzzData.mainEntity = entityInfo;
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}
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num++;
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}
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}
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}
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/**
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* xmlFuzzMainUrl:
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*
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* Returns the main URL.
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*/
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const char *
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xmlFuzzMainUrl(void) {
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return(fuzzData.mainUrl);
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}
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/**
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* xmlFuzzMainEntity:
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* @size: size of the main entity in bytes
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*
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* Returns the main entity.
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*/
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const char *
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xmlFuzzMainEntity(size_t *size) {
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if (fuzzData.mainEntity == NULL)
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return(NULL);
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*size = fuzzData.mainEntity->size;
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return(fuzzData.mainEntity->data);
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}
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/**
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* xmlFuzzResourceLoader:
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*
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* The resource loader for fuzz data.
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*/
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int
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xmlFuzzResourceLoader(void *data ATTRIBUTE_UNUSED, const char *URL,
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const char *ID ATTRIBUTE_UNUSED,
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xmlResourceType type ATTRIBUTE_UNUSED,
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int flags ATTRIBUTE_UNUSED, xmlParserInputPtr *out) {
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xmlParserInputPtr input;
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xmlFuzzEntityInfo *entity;
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entity = xmlHashLookup(fuzzData.entities, (xmlChar *) URL);
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if (entity == NULL)
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return(XML_IO_ENOENT);
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input = xmlInputCreateMemory(URL, entity->data, entity->size,
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XML_INPUT_BUF_STATIC |
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XML_INPUT_BUF_ZERO_TERMINATED);
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if (input == NULL)
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return(XML_ERR_NO_MEMORY);
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*out = input;
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return(XML_ERR_OK);
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}
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/**
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* xmlFuzzEntityLoader:
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*
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* The entity loader for fuzz data.
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*/
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xmlParserInputPtr
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xmlFuzzEntityLoader(const char *URL, const char *ID ATTRIBUTE_UNUSED,
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xmlParserCtxtPtr ctxt) {
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xmlParserInputBufferPtr buf;
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xmlFuzzEntityInfo *entity;
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if (URL == NULL)
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return(NULL);
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entity = xmlHashLookup(fuzzData.entities, (xmlChar *) URL);
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if (entity == NULL)
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return(NULL);
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buf = xmlParserInputBufferCreateMem(entity->data, entity->size,
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XML_CHAR_ENCODING_NONE);
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if (buf == NULL) {
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xmlCtxtErrMemory(ctxt);
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return(NULL);
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}
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return(xmlNewIOInputStream(ctxt, buf, XML_CHAR_ENCODING_NONE));
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}
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char *
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xmlSlurpFile(const char *path, size_t *sizeRet) {
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FILE *file;
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struct stat statbuf;
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char *data;
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size_t size;
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if ((stat(path, &statbuf) != 0) || (!S_ISREG(statbuf.st_mode)))
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return(NULL);
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size = statbuf.st_size;
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file = fopen(path, "rb");
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if (file == NULL)
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return(NULL);
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data = xmlMalloc(size + 1);
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if (data != NULL) {
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if (fread(data, 1, size, file) != size) {
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xmlFree(data);
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data = NULL;
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} else {
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data[size] = 0;
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if (sizeRet != NULL)
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*sizeRet = size;
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}
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}
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fclose(file);
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return(data);
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}
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