fix default limiter overflow (#3338)

* add validation for negative elapsedtime

---------

Co-authored-by: root <root@jscs02-sh001-storage-uat-02>
Co-authored-by: sbera87 <[email protected]>

Author: 3 people

src/aws-cpp-sdk-core/include/aws/core/utils/ratelimiter/DefaultRateLimiter.h

@@ -61,15 +61,23 @@ class DefaultRateLimiter : public RateLimiterInterface {
     auto now = m_elapsedTimeFunction();
     auto elapsedTime = (now - m_accumulatorUpdated).count();
 
-    // replenish the accumulator based on how much time has passed
-    auto temp = elapsedTime * m_replenishNumerator + m_accumulatorFraction;
-    m_accumulator += temp / m_replenishDenominator;
-    m_accumulatorFraction = temp % m_replenishDenominator;
-
-    // the accumulator is capped based on the maximum rate
-    m_accumulator = (std::min)(m_accumulator, m_maxRate);
-    if (m_accumulator == m_maxRate) {
+    // check for overflow case
+    if (m_replenishNumerator != 0 && elapsedTime > 0 &&
+        (elapsedTime > std::numeric_limits<int64_t>::max() / m_replenishNumerator ||
+         m_accumulatorFraction > std::numeric_limits<int64_t>::max() - (elapsedTime * m_replenishNumerator))) {
+      m_accumulator = m_maxRate;
       m_accumulatorFraction = 0;
+    } else {
+      // replenish the accumulator based on how much time has passed
+      auto temp = elapsedTime * m_replenishNumerator + m_accumulatorFraction;
+      m_accumulator += temp / m_replenishDenominator;
+      m_accumulatorFraction = temp % m_replenishDenominator;
+
+      // the accumulator is capped based on the maximum rate
+      m_accumulator = (std::min)(m_accumulator, m_maxRate);
+      if (m_accumulator == m_maxRate) {
+        m_accumulatorFraction = 0;
+      }
     }
 
     // if the accumulator is still negative, then we'll have to wait

tests/aws-cpp-sdk-core-tests/utils/ratelimiter/RateLimiterTests.cpp

@@ -225,6 +225,24 @@ TEST_F(DefaultRateLimitTest, unnormalizedChangeRateLimitTest) {
   ASSERT_TRUE(delay.count() == 4910);
 }
 
+TEST_F(DefaultRateLimitTest, overflowTest) {
+  // 500MB/s
+  int max_rate = 500 * 1024 * 1024;
+  TestDefaultRateLimiter limiter(max_rate, DefaultRateLimitTest::GetTestTime);
+
+  // 7 days
+  int64_t time_elapsed = 7LL * 24 * 60 * 60 * 1000000;
+
+  limiter.ApplyCost(0);
+  auto delay = limiter.ApplyCost(0);
+  ASSERT_TRUE(delay.count() == 0);
+
+  // The original code here would cause the sleep duration to be excessively long
+  SetMillisecondsElapsed(time_elapsed);
+  delay = limiter.ApplyCost(0);
+  ASSERT_TRUE(delay.count() == 0);
+}
+
 TEST_F(DefaultRateLimitTest, fractionalLimitTest) {
   TestDefaultRateLimiter limiter(100, DefaultRateLimitTest::GetTestTime);