cbor_load_fuzzer.cc

#include <cstdint>
#include <cstdio>
#include <cstdlib>
#include <unordered_map>

#include "cbor.h"

static size_t allocated_mem = 0;
static std::unordered_map<void*, size_t> allocated_len_map;
static constexpr size_t kMemoryLimit = 1 << 30;

void *limited_malloc(size_t size) {
    if (size + allocated_mem > kMemoryLimit) {
        return nullptr;
    }
    if (size == 0) {
        return nullptr;
    }
    void* m = malloc(size);
    if (m != nullptr) {
        allocated_mem += size;
        allocated_len_map[m] = size;
    }
    return m;
}

void limited_free(void *ptr) {
    if (ptr != NULL && allocated_len_map.find(ptr) == allocated_len_map.end()) {
        abort();
    }
    free(ptr);
    if (ptr != NULL) {
        allocated_mem -= allocated_len_map[ptr];
        allocated_len_map.erase(ptr);
    }
}

void *limited_realloc(void *ptr, size_t size) {
    if (ptr != NULL && allocated_len_map.find(ptr) == allocated_len_map.end()) {
        abort();
    }
    if (ptr == NULL) {
        return limited_malloc(size);
    }
    long delta = (long) size - allocated_len_map[ptr];
    if (delta + allocated_mem > kMemoryLimit) {
        return nullptr;
    }
    void* new_ptr = realloc(ptr, size);
    if (size > 0 && new_ptr == nullptr) {
        return nullptr;
    }
    allocated_mem += delta;
    allocated_len_map.erase(ptr);
    if (size > 0) {
        allocated_len_map[new_ptr] = size;
    }
    return new_ptr;
}

struct State {
    FILE* fout;

    State() : fout(fopen("/dev/null", "r")) {
        cbor_set_allocs(limited_malloc, limited_realloc, limited_free);
    }
};

static State kState;

extern "C" int LLVMFuzzerTestOneInput(const uint8_t *Data, size_t Size) {
    cbor_load_result result;
    cbor_item_t *item = cbor_load(Data, Size, &result);
    if (result.error.code == CBOR_ERR_NONE) {
        cbor_describe(item, kState.fout);
        unsigned char *buffer;
        size_t buffer_size;
        cbor_serialize_alloc(item, &buffer, &buffer_size);
        free(buffer);
        cbor_item_t *copied = cbor_copy(item);
        cbor_decref(&copied);
        cbor_decref(&item);
    }
    return 0;
}