pkg/runtest: fix a race during startup

Run method usually runs in a separate goroutine concurrently with request consumer
(Next calls), so at least executor needs to be initialized before Run.
Otherwise we can get episodic nil derefs in Next method.

3 files changed, 9 insertions, 2 deletions

diff --git a/pkg/runtest/run.go b/pkg/runtest/run.go
index 501f92dd3..e0fefc31a 100644
--- a/pkg/runtest/run.go
+++ b/pkg/runtest/run.go
@@ -63,13 +63,18 @@ type Context struct {
 	buildSem chan bool
 }
 
+func (ctx *Context) Init() {
+	// Run usually runs in a separate goroutine concurrently with request consumer (Next calls),
+	// so at least executor needs to be initialized before Run.
+	ctx.executor = queue.DynamicOrder()
+	ctx.buildSem = make(chan bool, runtime.GOMAXPROCS(0))
+}
+
 func (ctx *Context) log(msg string, args ...interface{}) {
 	ctx.LogFunc(fmt.Sprintf(msg, args...))
 }
 
 func (ctx *Context) Run(waitCtx context.Context) error {
-	ctx.buildSem = make(chan bool, runtime.GOMAXPROCS(0))
-	ctx.executor = queue.DynamicOrder()
 	ctx.generatePrograms()
 	var ok, fail, broken, skip int
 	for _, req := range ctx.requests {
diff --git a/pkg/runtest/run_test.go b/pkg/runtest/run_test.go
index 0861b7e2b..d0c3ca780 100644
--- a/pkg/runtest/run_test.go
+++ b/pkg/runtest/run_test.go
@@ -85,6 +85,7 @@ func test(t *testing.T, sysTarget *targets.Target) {
 		Verbose: true,
 		Debug:   *flagDebug,
 	}
+	ctx.Init()
 	waitCtx := startRPCServer(t, target, executor, ctx, rpcParams{
 		manyProcs: true,
 		machineChecked: func(features flatrpc.Feature) {
diff --git a/syz-manager/manager.go b/syz-manager/manager.go
index 367ade170..52d50109e 100644
--- a/syz-manager/manager.go
+++ b/syz-manager/manager.go
@@ -1389,6 +1389,7 @@ func (mgr *Manager) MachineChecked(features flatrpc.Feature, enabledSyscalls map
 			Verbose: true,
 			Debug:   *flagDebug,
 		}
+		ctx.Init()
 		go func() {
 			err := ctx.Run(context.Background())
 			if err != nil {