oss-fuzz: add fuzzer for parsing reftables

Add a new fuzzer that exercises our parsing of reftables. Fallout from
this fuzzer will be fixed over subsequent commits.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Makefile

@@ -2603,6 +2603,7 @@ FUZZ_OBJS += oss-fuzz/fuzz-date.o
 FUZZ_OBJS += oss-fuzz/fuzz-pack-headers.o
 FUZZ_OBJS += oss-fuzz/fuzz-pack-idx.o
 FUZZ_OBJS += oss-fuzz/fuzz-parse-attr-line.o
+FUZZ_OBJS += oss-fuzz/fuzz-reftable.o
 FUZZ_OBJS += oss-fuzz/fuzz-url-decode-mem.o
 .PHONY: fuzz-objs
 fuzz-objs: $(FUZZ_OBJS)

ci/run-build-and-minimal-fuzzers.sh

@@ -21,6 +21,7 @@ date
 pack-headers
 pack-idx
 parse-attr-line
+reftable
 url-decode-mem
 "
 

oss-fuzz/.gitignore

@@ -5,4 +5,5 @@ fuzz-date
 fuzz-pack-headers
 fuzz-pack-idx
 fuzz-parse-attr-line
+fuzz-reftable
 fuzz-url-decode-mem

oss-fuzz/fuzz-reftable.c

@@ -0,0 +1,74 @@
+#include "git-compat-util.h"
+#include "reftable/basics.h"
+#include "reftable/blocksource.h"
+#include "reftable/reftable-blocksource.h"
+#include "reftable/reftable-error.h"
+#include "reftable/reftable-iterator.h"
+#include "reftable/reftable-record.h"
+#include "reftable/reftable-table.h"
+#include "reftable/reftable-writer.h"
+
+int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size);
+
+int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size)
+{
+	struct reftable_block_source source = { 0 };
+	struct reftable_buf buf = REFTABLE_BUF_INIT;
+	struct reftable_table *table = NULL;
+	int err;
+
+	if (reftable_buf_add(&buf, (const char *)data, size) < 0)
+		goto out;
+	block_source_from_buf(&source, &buf);
+
+	err = reftable_table_new(&table, &source, "fuzz-input");
+	if (err < 0)
+		goto out;
+
+	/*
+	 * Exercise the ref, log and raw block iterators so that we cover as
+	 * much of the parsing code as possible.
+	 */
+	{
+		struct reftable_ref_record ref = { 0 };
+		struct reftable_iterator it = { 0 };
+
+		reftable_table_init_ref_iterator(table, &it);
+		if (!reftable_iterator_seek_ref(&it, ""))
+			while (!reftable_iterator_next_ref(&it, &ref))
+				;
+
+		reftable_ref_record_release(&ref);
+		reftable_iterator_destroy(&it);
+	}
+
+	{
+		struct reftable_log_record log = { 0 };
+		struct reftable_iterator it = { 0 };
+
+		reftable_table_init_log_iterator(table, &it);
+		if (!reftable_iterator_seek_log(&it, ""))
+			while (!reftable_iterator_next_log(&it, &log))
+				;
+
+		reftable_log_record_release(&log);
+		reftable_iterator_destroy(&it);
+	}
+
+	{
+		struct reftable_table_iterator it = { 0 };
+		const struct reftable_block *block;
+
+		if (!reftable_table_iterator_init(&it, table))
+			while (!reftable_table_iterator_next(&it, &block))
+				;
+
+		reftable_table_iterator_release(&it);
+	}
+
+out:
+	if (table)
+		reftable_table_decref(table);
+	reftable_buf_release(&buf);
+	return 0;
+}

oss-fuzz/meson.build

@@ -6,6 +6,7 @@ fuzz_programs = [
   'fuzz-pack-headers.c',
   'fuzz-pack-idx.c',
   'fuzz-parse-attr-line.c',
+  'fuzz-reftable.c',
   'fuzz-url-decode-mem.c',
 ]