Depending on the dump_mode byte, dump out as a string or as a callback.
@@ -23,16 +23,22 @@ static int json_dump_counter(const char *buffer, size_t size, void *data)
}
+#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;
// 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 < sizeof(size_t) + sizeof(size_t))
+ if (size < NUM_COMMAND_BYTES)
{
return 0;
}
@@ -40,7 +46,6 @@ 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"
@@ -58,7 +63,6 @@ extern "C" int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size)
// 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"
@@ -81,6 +85,15 @@ extern "C" int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size)
((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);
json_t* jobj = json_loadb(text, size, load_flags, &error);
@@ -90,11 +103,25 @@ extern "C" int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size)
return 0;
}
+ if (dump_mode & FUZZ_DUMP_STRING)
+ {
+ // 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)
{
