syz-cluster: skip fuzzing if binaries are the same

If all symbol hashes between the base and the pathed kernel match,
there's no reason to spend time fuzzing the series.

Add a 'skipped' status to the enum of possible session test results and
set it from the fuzz-step.

5 files changed, 54 insertions, 1 deletions

diff --git a/syz-cluster/pkg/api/api.go b/syz-cluster/pkg/api/api.go
index 60c106254..65f0f4bd2 100644
--- a/syz-cluster/pkg/api/api.go
+++ b/syz-cluster/pkg/api/api.go
@@ -73,6 +73,7 @@ type Build struct {
 const (
 	TestRunning string = "running"
 	TestPassed  string = "passed"
+	TestSkipped string = "skipped"
 	TestFailed  string = "failed" // TODO: drop it? only mark completion?
 	TestError   string = "error"
 )
diff --git a/syz-cluster/pkg/db/migrations/5_session_test_skipped.down.sql b/syz-cluster/pkg/db/migrations/5_session_test_skipped.down.sql
new file mode 100644
index 000000000..dbda912f2
--- /dev/null
+++ b/syz-cluster/pkg/db/migrations/5_session_test_skipped.down.sql
@@ -0,0 +1,3 @@
+ALTER TABLE SessionTests DROP CONSTRAINT ResultEnum;
+ALTER TABLE SessionTests ADD CONSTRAINT ResultEnum CHECK (Result IN ('passed', 'failed', 'error', 'running'));
+DROP INDEX SessionTestsByResult;
diff --git a/syz-cluster/pkg/db/migrations/5_session_test_skipped.up.sql b/syz-cluster/pkg/db/migrations/5_session_test_skipped.up.sql
new file mode 100644
index 000000000..8509fd816
--- /dev/null
+++ b/syz-cluster/pkg/db/migrations/5_session_test_skipped.up.sql
@@ -0,0 +1,3 @@
+ALTER TABLE SessionTests DROP CONSTRAINT ResultEnum;
+ALTER TABLE SessionTests ADD CONSTRAINT ResultEnum CHECK (Result IN ('passed', 'failed', 'error', 'running', 'skipped'));
+CREATE INDEX SessionTestsByResult ON SessionTests(SessionID, Result);
diff --git a/syz-cluster/workflow/fuzz-step/main.go b/syz-cluster/workflow/fuzz-step/main.go
index 77432ec4f..954c9d25c 100644
--- a/syz-cluster/workflow/fuzz-step/main.go
+++ b/syz-cluster/workflow/fuzz-step/main.go
@@ -68,7 +68,9 @@ func main() {
 	defer cancel()
 	err = run(runCtx, client, d, store)
 	status := api.TestPassed // TODO: what about TestFailed?
-	if err != nil && !errors.Is(err, context.DeadlineExceeded) {
+	if errors.Is(err, errSkipFuzzing) {
+		status = api.TestSkipped
+	} else if err != nil && !errors.Is(err, context.DeadlineExceeded) {
 		app.Errorf("the step failed: %v", err)
 		status = api.TestError
 	}
@@ -79,6 +81,8 @@ func main() {
 	}
 }
 
+var errSkipFuzzing = errors.New("skip")
+
 func run(baseCtx context.Context, client *api.Client, timeout time.Duration,
 	store *manager.DiffFuzzerStore) error {
 	series, err := client.GetSessionSeries(baseCtx, *flagSession)
@@ -100,6 +104,10 @@ func run(baseCtx context.Context, client *api.Client, timeout time.Duration,
 	if err != nil {
 		app.Errorf("failed to read symbol hashes: %v", err)
 	}
+
+	if shouldSkipFuzzing(baseSymbols, patchedSymbols) {
+		return errSkipFuzzing
+	}
 	manager.PatchFocusAreas(patched, series.PatchBodies(), baseSymbols, patchedSymbols)
 
 	if *flagCorpusURL != "" {
@@ -288,6 +296,24 @@ func reportFinding(ctx context.Context, client *api.Client, bug *manager.UniqueB
 	return client.UploadFinding(ctx, finding)
 }
 
+func shouldSkipFuzzing(baseSymbols, patchedSymbols map[string]string) bool {
+	if len(baseSymbols) == 0 || len(patchedSymbols) == 0 {
+		// Likely, something went wrong during the kernel build step.
+		log.Logf(0, "skipped the binary equality check because some of them have 0 symbols")
+		return false
+	}
+	if len(baseSymbols) == len(patchedSymbols) {
+		for name, hash := range baseSymbols {
+			if patchedSymbols[name] != hash {
+				log.Logf(0, "binaries are different, continuing fuzzing")
+				return false
+			}
+		}
+	}
+	log.Logf(0, "binaries are the same, no sense to do fuzzing")
+	return true
+}
+
 func readSymbolHashes() (base, patched map[string]string, err error) {
 	// These are saved by the build step.
 	base, err = readJSONMap("/base/symbol_hashes.json")
diff --git a/syz-cluster/workflow/fuzz-step/main_test.go b/syz-cluster/workflow/fuzz-step/main_test.go
index fa339f451..49ec3b330 100644
--- a/syz-cluster/workflow/fuzz-step/main_test.go
+++ b/syz-cluster/workflow/fuzz-step/main_test.go
@@ -7,6 +7,8 @@ import (
 	"io/fs"
 	"path/filepath"
 	"testing"
+
+	"github.com/stretchr/testify/assert"
 )
 
 func TestConfigLoad(t *testing.T) {
@@ -26,3 +28,21 @@ func TestConfigLoad(t *testing.T) {
 		return nil
 	})
 }
+
+func TestShouldSkipFuzzing(t *testing.T) {
+	t.Run("one empty", func(t *testing.T) {
+		assert.False(t, shouldSkipFuzzing(nil, map[string]string{"A": "1"}))
+	})
+	t.Run("equal", func(t *testing.T) {
+		assert.True(t, shouldSkipFuzzing(
+			map[string]string{"A": "1", "B": "2"},
+			map[string]string{"A": "1", "B": "2"},
+		))
+	})
+	t.Run("different", func(t *testing.T) {
+		assert.False(t, shouldSkipFuzzing(
+			map[string]string{"A": "1", "B": "2"},
+			map[string]string{"A": "1", "B": "different"},
+		))
+	})
+}