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/*
* Copyright (C) 2022 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/* Ensure assert() catches logical errors during fuzzing */
#ifdef NDEBUG
#undef NDEBUG
#endif
#include <inttypes.h>
#include <assert.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
#include <sanitizer/asan_interface.h>
#include <sanitizer/msan_interface.h>
#include "libfdt.h"
#include "libfdt_env.h"
/* check memory region is valid, for the purpose of tooling such as asan */
static void check_mem(const void *mem, size_t len) {
assert(mem);
#if __has_feature(memory_sanitizer)
/* dumps if check fails */
__msan_check_mem_is_initialized((void *)mem, len);
#endif
#if __has_feature(address_sanitizer) || defined(__SANITIZE_ADDRESS__)
assert(!__asan_region_is_poisoned((void *)mem, len));
#else
const volatile uint8_t *mem8 = mem;
/* Read each byte of memory for instrumentation */
for(size_t i = 0; i < len; i++) {
(void)mem8[i];
}
#endif
}
static bool phandle_is_valid(uint32_t phandle) {
return phandle != 0 && phandle != UINT32_MAX;
}
static void walk_node_properties(const void *device_tree, int node) {
int property, len = 0;
fdt_for_each_property_offset(property, device_tree, node) {
const struct fdt_property *prop = fdt_get_property_by_offset(device_tree,
property, &len);
if (!prop)
continue;
check_mem(prop->data, fdt32_to_cpu(prop->len));
const char *prop_name = fdt_string(device_tree, prop->nameoff);
if (prop_name != NULL) {
check_mem(prop_name, strlen(prop_name));
}
}
}
static void walk_device_tree(const void *device_tree, int parent_node) {
int len = 0;
const char *node_name = fdt_get_name(device_tree, parent_node, &len);
if (node_name != NULL) {
check_mem(node_name, len);
}
uint32_t phandle = fdt_get_phandle(device_tree, parent_node);
if (phandle_is_valid(phandle)) {
int node = fdt_node_offset_by_phandle(device_tree, phandle);
assert(node >= 0); // it should at least find parent_node
}
char path_buf[64];
if(fdt_get_path(device_tree, parent_node, path_buf, sizeof(path_buf)) == 0) {
fdt_path_offset(device_tree, path_buf);
}
fdt_parent_offset(device_tree, parent_node);
// Exercise sub-node search string functions
fdt_subnode_offset(device_tree, parent_node, "a");
fdt_get_property(device_tree, parent_node, "reg", &len);
// Check for a stringlist node called 'stringlist' (added to corpus)
const int sl_count = fdt_stringlist_count(device_tree,
parent_node, "stringlist");
if (sl_count > 0) {
for (int i = 0; i < sl_count; i++) {
fdt_stringlist_get(device_tree, parent_node, "stringlist", i, &len);
}
fdt_stringlist_search(device_tree, parent_node, "stringlist", "a");
}
walk_node_properties(device_tree, parent_node);
// recursively walk the node's children
for (int node = fdt_first_subnode(device_tree, parent_node); node >= 0;
node = fdt_next_subnode(device_tree, node)) {
walk_device_tree(device_tree, node);
}
}
static void walk_mem_rsv(const void *device_tree) {
const int n = fdt_num_mem_rsv(device_tree);
uint64_t address, size;
for (int i = 0; i < n; i++) {
fdt_get_mem_rsv(device_tree, i, &address, &size);
}
}
// Information on device tree is available in external/dtc/Documentation/
// folder.
int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
int rc;
// Non-zero return values are reserved for future use.
if (size < FDT_V17_SIZE) return 0;
// Produce coverage of checking function
rc = fdt_check_full(data, size);
fdt_strerror(rc);
// Don't continue if the library rejected the input
if (rc != 0) return 0;
// Cover reading functions
walk_device_tree(data, /* parent_node */ 0);
walk_mem_rsv(data);
// Cover phandle functions
uint32_t phandle;
fdt_generate_phandle(data, &phandle);
// Try and get a path by alias
fdt_path_offset(data, "a");
// Try to get an alias
fdt_get_alias(data, "a");
// Exercise common search functions
fdt_node_offset_by_compatible(data, 0, "a");
fdt_node_offset_by_prop_value(data, 0, "x", "42", 3);
return 0;
}
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