Merge pull request #31396 from foxish/integer-overflow

Automatic merge from submit-queue

Fixed integer overflow bug in rate limiter.

```release-note
Fix overflow issue in controller-manager rate limiter
```

This PR fixes a bug in the delayed work-queue used by some controllers.
The integer overflow bug would previously cause hotlooping behavior after a few failures 
as `time.Duration(..)` on values larger than MaxInt64 behaves unpredictably, and 
after a certain value returns 0 always.

cc @bprashanth @pwittrock

pkg/util/workqueue/default_rate_limiters.go

@@ -90,9 +90,16 @@ func (r *ItemExponentialFailureRateLimiter) When(item interface{}) time.Duration
 	r.failuresLock.Lock()
 	defer r.failuresLock.Unlock()
 
+	exp := r.failures[item]
 	r.failures[item] = r.failures[item] + 1
 
-	calculated := r.baseDelay * time.Duration(math.Pow10(r.failures[item]-1))
+	// The backoff is capped such that 'calculated' value never overflows.
+	backoff := float64(r.baseDelay.Nanoseconds()) * math.Pow10(exp)
+	if backoff > math.MaxInt64 {
+		return r.maxDelay
+	}
+
+	calculated := time.Duration(backoff)
 	if calculated > r.maxDelay {
 		return r.maxDelay
 	}

pkg/util/workqueue/default_rate_limiters_test.go

@@ -63,6 +63,39 @@ func TestItemExponentialFailureRateLimiter(t *testing.T) {
 
 }
 
+func TestItemExponentialFailureRateLimiterOverFlow(t *testing.T) {
+	limiter := NewItemExponentialFailureRateLimiter(1*time.Millisecond, 1000*time.Second)
+	for i := 0; i < 5; i++ {
+		limiter.When("one")
+	}
+	if e, a := 100000*time.Millisecond, limiter.When("one"); e != a {
+		t.Errorf("expected %v, got %v", e, a)
+	}
+
+	for i := 0; i < 1000; i++ {
+		limiter.When("overflow1")
+	}
+	if e, a := 1000*time.Second, limiter.When("overflow1"); e != a {
+		t.Errorf("expected %v, got %v", e, a)
+	}
+
+	limiter = NewItemExponentialFailureRateLimiter(1*time.Minute, 1000*time.Hour)
+	for i := 0; i < 2; i++ {
+		limiter.When("two")
+	}
+	if e, a := 100*time.Minute, limiter.When("two"); e != a {
+		t.Errorf("expected %v, got %v", e, a)
+	}
+
+	for i := 0; i < 1000; i++ {
+		limiter.When("overflow2")
+	}
+	if e, a := 1000*time.Hour, limiter.When("overflow2"); e != a {
+		t.Errorf("expected %v, got %v", e, a)
+	}
+
+}
+
 func TestItemFastSlowRateLimiter(t *testing.T) {
 	limiter := NewItemFastSlowRateLimiter(5*time.Millisecond, 10*time.Second, 3)