Hash :
df40f64e
Author :
Date :
2024-06-13T18:00:33
fuzz: Avoid accessing internal struct members Switch to xmlNewIOInputStream.
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/*
* fuzz.c: Common functions for fuzzing.
*
* See Copyright for the status of this software.
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
#include <libxml/hash.h>
#include <libxml/parser.h>
#include <libxml/parserInternals.h>
#include <libxml/tree.h>
#include <libxml/xmlIO.h>
#include "fuzz.h"
typedef struct {
const char *data;
size_t size;
} xmlFuzzEntityInfo;
/* Single static instance for now */
static struct {
/* Original data */
const char *data;
size_t size;
/* Remaining data */
const char *ptr;
size_t remaining;
/* Buffer for unescaped strings */
char *outBuf;
char *outPtr; /* Free space at end of buffer */
xmlHashTablePtr entities; /* Maps URLs to xmlFuzzEntityInfos */
/* The first entity is the main entity. */
const char *mainUrl;
xmlFuzzEntityInfo *mainEntity;
} fuzzData;
size_t fuzzNumAllocs;
size_t fuzzMaxAllocs;
int fuzzAllocFailed;
/**
* xmlFuzzErrorFunc:
*
* An error function that simply discards all errors.
*/
void
xmlFuzzErrorFunc(void *ctx ATTRIBUTE_UNUSED, const char *msg ATTRIBUTE_UNUSED,
...) {
}
/**
* xmlFuzzSErrorFunc:
*
* A structured error function that simply discards all errors.
*/
void
xmlFuzzSErrorFunc(void *ctx ATTRIBUTE_UNUSED,
const xmlError *error ATTRIBUTE_UNUSED) {
}
/*
* Malloc failure injection.
*
* To debug issues involving malloc failures, it's often helpful to set
* MALLOC_ABORT to 1. This should provide a backtrace of the failed
* allocation.
*/
#define XML_FUZZ_MALLOC_ABORT 0
static void *
xmlFuzzMalloc(size_t size) {
void *ret;
if (fuzzMaxAllocs > 0) {
fuzzNumAllocs += 1;
if (fuzzNumAllocs == fuzzMaxAllocs) {
#if XML_FUZZ_MALLOC_ABORT
abort();
#endif
fuzzAllocFailed = 1;
return NULL;
}
}
ret = malloc(size);
if (ret == NULL)
fuzzAllocFailed = 1;
return ret;
}
static void *
xmlFuzzRealloc(void *ptr, size_t size) {
void *ret;
if (fuzzMaxAllocs > 0) {
fuzzNumAllocs += 1;
if (fuzzNumAllocs == fuzzMaxAllocs) {
#if XML_FUZZ_MALLOC_ABORT
abort();
#endif
fuzzAllocFailed = 1;
return NULL;
}
}
ret = realloc(ptr, size);
if (ret == NULL)
fuzzAllocFailed = 1;
return ret;
}
void
xmlFuzzMemSetup(void) {
xmlMemSetup(free, xmlFuzzMalloc, xmlFuzzRealloc, xmlMemStrdup);
}
void
xmlFuzzMemSetLimit(size_t limit) {
fuzzNumAllocs = 0;
fuzzMaxAllocs = limit;
fuzzAllocFailed = 0;
}
int
xmlFuzzMallocFailed(void) {
return fuzzAllocFailed;
}
void
xmlFuzzResetMallocFailed(void) {
fuzzAllocFailed = 0;
}
void
xmlFuzzCheckMallocFailure(const char *func, int error) {
if (error >= 0 && fuzzAllocFailed != error) {
fprintf(stderr, "%s: malloc failure %s reported\n",
func, fuzzAllocFailed ? "not" : "erroneously");
abort();
}
fuzzAllocFailed = 0;
}
/**
* xmlFuzzDataInit:
*
* Initialize fuzz data provider.
*/
void
xmlFuzzDataInit(const char *data, size_t size) {
fuzzData.data = data;
fuzzData.size = size;
fuzzData.ptr = data;
fuzzData.remaining = size;
fuzzData.outBuf = xmlMalloc(size + 1);
fuzzData.outPtr = fuzzData.outBuf;
fuzzData.entities = xmlHashCreate(8);
fuzzData.mainUrl = NULL;
fuzzData.mainEntity = NULL;
}
/**
* xmlFuzzDataFree:
*
* Cleanup fuzz data provider.
*/
void
xmlFuzzDataCleanup(void) {
xmlFree(fuzzData.outBuf);
xmlHashFree(fuzzData.entities, xmlHashDefaultDeallocator);
}
/**
* xmlFuzzWriteInt:
* @out: output file
* @v: integer to write
* @size: size of integer in bytes
*
* Write an integer to the fuzz data.
*/
void
xmlFuzzWriteInt(FILE *out, size_t v, int size) {
int shift;
while (size > (int) sizeof(size_t)) {
putc(0, out);
size--;
}
shift = size * 8;
while (shift > 0) {
shift -= 8;
putc((v >> shift) & 255, out);
}
}
/**
* xmlFuzzReadInt:
* @size: size of integer in bytes
*
* Read an integer from the fuzz data.
*/
size_t
xmlFuzzReadInt(int size) {
size_t ret = 0;
while ((size > 0) && (fuzzData.remaining > 0)) {
unsigned char c = (unsigned char) *fuzzData.ptr++;
fuzzData.remaining--;
ret = (ret << 8) | c;
size--;
}
return ret;
}
/**
* xmlFuzzBytesRemaining:
*
* Return number of remaining bytes in fuzz data.
*/
size_t
xmlFuzzBytesRemaining(void) {
return(fuzzData.remaining);
}
/**
* xmlFuzzReadRemaining:
* @size: size of string in bytes
*
* Read remaining bytes from fuzz data.
*/
const char *
xmlFuzzReadRemaining(size_t *size) {
const char *ret = fuzzData.ptr;
*size = fuzzData.remaining;
fuzzData.ptr += fuzzData.remaining;
fuzzData.remaining = 0;
return(ret);
}
/*
* xmlFuzzWriteString:
* @out: output file
* @str: string to write
*
* Write a random-length string to file in a format similar to
* FuzzedDataProvider. Backslash followed by newline marks the end of the
* string. Two backslashes are used to escape a backslash.
*/
void
xmlFuzzWriteString(FILE *out, const char *str) {
for (; *str; str++) {
int c = (unsigned char) *str;
putc(c, out);
if (c == '\\')
putc(c, out);
}
putc('\\', out);
putc('\n', out);
}
/**
* xmlFuzzReadString:
* @size: size of string in bytes
*
* Read a random-length string from the fuzz data.
*
* The format is similar to libFuzzer's FuzzedDataProvider but treats
* backslash followed by newline as end of string. This makes the fuzz data
* more readable. A backslash character is escaped with another backslash.
*
* Returns a zero-terminated string or NULL if the fuzz data is exhausted.
*/
const char *
xmlFuzzReadString(size_t *size) {
const char *out = fuzzData.outPtr;
while (fuzzData.remaining > 0) {
int c = *fuzzData.ptr++;
fuzzData.remaining--;
if ((c == '\\') && (fuzzData.remaining > 0)) {
int c2 = *fuzzData.ptr;
if (c2 == '\n') {
fuzzData.ptr++;
fuzzData.remaining--;
if (size != NULL)
*size = fuzzData.outPtr - out;
*fuzzData.outPtr++ = '\0';
return(out);
}
if (c2 == '\\') {
fuzzData.ptr++;
fuzzData.remaining--;
}
}
*fuzzData.outPtr++ = c;
}
if (fuzzData.outPtr > out) {
if (size != NULL)
*size = fuzzData.outPtr - out;
*fuzzData.outPtr++ = '\0';
return(out);
}
if (size != NULL)
*size = 0;
return(NULL);
}
/**
* xmlFuzzReadEntities:
*
* Read entities like the main XML file, external DTDs, external parsed
* entities from fuzz data.
*/
void
xmlFuzzReadEntities(void) {
size_t num = 0;
while (1) {
const char *url, *entity;
size_t urlSize, entitySize;
xmlFuzzEntityInfo *entityInfo;
url = xmlFuzzReadString(&urlSize);
if (url == NULL) break;
entity = xmlFuzzReadString(&entitySize);
if (entity == NULL) break;
/*
* Cap URL size to avoid quadratic behavior when generating
* error messages or looking up entities.
*/
if (urlSize < 50 &&
xmlHashLookup(fuzzData.entities, (xmlChar *)url) == NULL) {
entityInfo = xmlMalloc(sizeof(xmlFuzzEntityInfo));
if (entityInfo == NULL)
break;
entityInfo->data = entity;
entityInfo->size = entitySize;
xmlHashAddEntry(fuzzData.entities, (xmlChar *)url, entityInfo);
if (num == 0) {
fuzzData.mainUrl = url;
fuzzData.mainEntity = entityInfo;
}
num++;
}
}
}
/**
* xmlFuzzMainUrl:
*
* Returns the main URL.
*/
const char *
xmlFuzzMainUrl(void) {
return(fuzzData.mainUrl);
}
/**
* xmlFuzzMainEntity:
* @size: size of the main entity in bytes
*
* Returns the main entity.
*/
const char *
xmlFuzzMainEntity(size_t *size) {
if (fuzzData.mainEntity == NULL)
return(NULL);
*size = fuzzData.mainEntity->size;
return(fuzzData.mainEntity->data);
}
/**
* xmlFuzzResourceLoader:
*
* The resource loader for fuzz data.
*/
int
xmlFuzzResourceLoader(void *data ATTRIBUTE_UNUSED, const char *URL,
const char *ID ATTRIBUTE_UNUSED,
xmlResourceType type ATTRIBUTE_UNUSED,
int flags ATTRIBUTE_UNUSED, xmlParserInputPtr *out) {
xmlParserInputPtr input;
xmlFuzzEntityInfo *entity;
entity = xmlHashLookup(fuzzData.entities, (xmlChar *) URL);
if (entity == NULL)
return(XML_IO_ENOENT);
input = xmlInputCreateMemory(URL, entity->data, entity->size,
XML_INPUT_BUF_STATIC |
XML_INPUT_BUF_ZERO_TERMINATED);
if (input == NULL)
return(XML_ERR_NO_MEMORY);
*out = input;
return(XML_ERR_OK);
}
/**
* xmlFuzzEntityLoader:
*
* The entity loader for fuzz data.
*/
xmlParserInputPtr
xmlFuzzEntityLoader(const char *URL, const char *ID ATTRIBUTE_UNUSED,
xmlParserCtxtPtr ctxt) {
xmlParserInputBufferPtr buf;
xmlFuzzEntityInfo *entity;
if (URL == NULL)
return(NULL);
entity = xmlHashLookup(fuzzData.entities, (xmlChar *) URL);
if (entity == NULL)
return(NULL);
buf = xmlParserInputBufferCreateMem(entity->data, entity->size,
XML_CHAR_ENCODING_NONE);
if (buf == NULL) {
xmlCtxtErrMemory(ctxt);
return(NULL);
}
return(xmlNewIOInputStream(ctxt, buf, XML_CHAR_ENCODING_NONE));
}
char *
xmlSlurpFile(const char *path, size_t *sizeRet) {
FILE *file;
struct stat statbuf;
char *data;
size_t size;
if ((stat(path, &statbuf) != 0) || (!S_ISREG(statbuf.st_mode)))
return(NULL);
size = statbuf.st_size;
file = fopen(path, "rb");
if (file == NULL)
return(NULL);
data = xmlMalloc(size + 1);
if (data != NULL) {
if (fread(data, 1, size, file) != size) {
xmlFree(data);
data = NULL;
} else {
data[size] = 0;
if (sizeRet != NULL)
*sizeRet = size;
}
}
fclose(file);
return(data);
}