proc: fix escapeCheck infinite recursion if something can not be

_fixtures/reflecttypefncall.go

@@ -0,0 +1,16 @@
+package main
+
+import (
+	"fmt"
+	"reflect"
+)
+
+func reflectFunc(value reflect.Value) {
+	fmt.Printf("%s\n", value.Type().Name())
+}
+
+func main() {
+	i := 2
+	val := reflect.ValueOf(i)
+	reflectFunc(val)
+}

pkg/proc/fncall.go

@@ -760,6 +760,9 @@ func alignAddr(addr, align int64) int64 {
 }
 
 func escapeCheck(v *Variable, name string, stack stack) error {
+	if v.Unreadable != nil {
+		return fmt.Errorf("escape check for %s failed, variable unreadable: %v", name, v.Unreadable)
+	}
 	switch v.Kind {
 	case reflect.Ptr:
 		var w *Variable

pkg/proc/proc_test.go

@@ -6043,3 +6043,13 @@ func TestFollowExec(t *testing.T) {
 		}
 	})
 }
+
+func TestEscapeCheckUnreadable(t *testing.T) {
+	// A failure in escapeCheck to dereference a field should not cause
+	// infinite recursion. See issue #3310.
+	withTestProcessArgs("reflecttypefncall", t, ".", []string{}, protest.AllNonOptimized, func(p *proc.Target, grp *proc.TargetGroup, fixture protest.Fixture) {
+		setFileBreakpoint(p, t, fixture.Source, 9)
+		assertNoError(grp.Continue(), t, "Continue")
+		proc.EvalExpressionWithCalls(grp, p.SelectedGoroutine(), "value.Type()", normalLoadConfig, true)
+	})
+}