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Merge pull request #485 from cmeister2/cmeister2/fuzzerdiags

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ossfuzz: Improvements to json_load_dump_fuzzer
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Corey Farrell 2019-07-26 08:58:16 -04:00 committed by GitHub
commit a6f6ec1856
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GPG Key ID: 4AEE18F83AFDEB23
1 changed files with 93 additions and 8 deletions
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101
test/ossfuzz/json_load_dump_fuzzer.cc
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@ -1,13 +1,44 @@
#include <stdint.h>
#include <stdlib.h>
#include <sys/types.h>
#include <inttypes.h>
#include "jansson.h"
static int enable_diags;
#define FUZZ_DEBUG(FMT, ...) \
if (enable_diags) \
{ \
fprintf(stderr, FMT, ##__VA_ARGS__); \
fprintf(stderr, "\n"); \
}
static int json_dump_counter(const char *buffer, size_t size, void *data)
{
uint64_t *counter = reinterpret_cast<uint64_t *>(data);
*counter += size;
return 0;
}
#define NUM_COMMAND_BYTES (sizeof(size_t) + sizeof(size_t) + 1)
#define FUZZ_DUMP_CALLBACK 0x00
#define FUZZ_DUMP_STRING 0x01
extern "C" int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size)
{
json_error_t error;
unsigned char dump_mode;
if (size < sizeof(size_t) + sizeof(size_t))
// Enable or disable diagnostics based on the FUZZ_VERBOSE environment flag.
enable_diags = (getenv("FUZZ_VERBOSE") != NULL);
FUZZ_DEBUG("Input data length: %zd", size);
if (size < NUM_COMMAND_BYTES)
{
return 0;
}
@ -15,12 +46,53 @@ extern "C" int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size)
// Use the first sizeof(size_t) bytes as load flags.
size_t load_flags = *(const size_t*)data;
data += sizeof(size_t);
size -= sizeof(size_t);
FUZZ_DEBUG("load_flags: 0x%zx\n"
"& JSON_REJECT_DUPLICATES = 0x%zx\n"
"& JSON_DECODE_ANY = 0x%zx\n"
"& JSON_DISABLE_EOF_CHECK = 0x%zx\n"
"& JSON_DECODE_INT_AS_REAL = 0x%zx\n"
"& JSON_ALLOW_NUL = 0x%zx\n",
load_flags,
load_flags & JSON_REJECT_DUPLICATES,
load_flags & JSON_DECODE_ANY,
load_flags & JSON_DISABLE_EOF_CHECK,
load_flags & JSON_DECODE_INT_AS_REAL,
load_flags & JSON_ALLOW_NUL);
// Use the next sizeof(size_t) bytes as dump flags.
size_t dump_flags = *(const size_t*)data;
data += sizeof(size_t);
size -= sizeof(size_t);
FUZZ_DEBUG("dump_flags: 0x%zx\n"
"& JSON_MAX_INDENT = 0x%zx\n"
"& JSON_COMPACT = 0x%zx\n"
"& JSON_ENSURE_ASCII = 0x%zx\n"
"& JSON_SORT_KEYS = 0x%zx\n"
"& JSON_PRESERVE_ORDER = 0x%zx\n"
"& JSON_ENCODE_ANY = 0x%zx\n"
"& JSON_ESCAPE_SLASH = 0x%zx\n"
"& JSON_REAL_PRECISION = 0x%zx\n"
"& JSON_EMBED = 0x%zx\n",
dump_flags,
dump_flags & JSON_MAX_INDENT,
dump_flags & JSON_COMPACT,
dump_flags & JSON_ENSURE_ASCII,
dump_flags & JSON_SORT_KEYS,
dump_flags & JSON_PRESERVE_ORDER,
dump_flags & JSON_ENCODE_ANY,
dump_flags & JSON_ESCAPE_SLASH,
((dump_flags >> 11) & 0x1F) << 11,
dump_flags & JSON_EMBED);
// Use the next byte as the dump mode.
dump_mode = data[0];
data++;
FUZZ_DEBUG("dump_mode: 0x%x", (unsigned int)dump_mode);
// Remove the command bytes from the size total.
size -= NUM_COMMAND_BYTES;
// Attempt to load the remainder of the data with the given load flags.
const char* text = reinterpret_cast<const char *>(data);
@ -31,11 +103,24 @@ extern "C" int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size)
return 0;
}
// Attempt to dump the loaded json object with the given dump flags.
char* out = json_dumps(jobj, dump_flags);
if (out)
if (dump_mode & FUZZ_DUMP_STRING)
{
free(out);
// Dump as a string. Remove indents so that we don't run out of memory.
char *out = json_dumps(jobj, dump_flags & ~JSON_MAX_INDENT);
if (out != NULL)
{
free(out);
}
}
else
{
// Default is callback mode.
//
// Attempt to dump the loaded json object with the given dump flags.
uint64_t counter = 0;
json_dump_callback(jobj, json_dump_counter, &counter, dump_flags);
FUZZ_DEBUG("Counter function counted %" PRIu64 " bytes.", counter);
}
if (jobj)
@ -44,4 +129,4 @@ extern "C" int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size)
}
return 0;
}
}