[fuzz] Fixed divide by zero bug

source/extensions/filters/http/admission_control/config.cc

@@ -1,5 +1,6 @@
 #include "extensions/filters/http/admission_control/config.h"
 
+#include "envoy/common/exception.h"
 #include "envoy/extensions/filters/http/admission_control/v3alpha/admission_control.pb.h"
 #include "envoy/extensions/filters/http/admission_control/v3alpha/admission_control.pb.validate.h"
 #include "envoy/registry/registry.h"
@@ -21,6 +22,10 @@ Http::FilterFactoryCb AdmissionControlFilterFactory::createFilterFactoryFromProt
     const envoy::extensions::filters::http::admission_control::v3alpha::AdmissionControl& config,
     const std::string& stats_prefix, Server::Configuration::FactoryContext& context) {
 
+  if (config.has_sr_threshold() && config.sr_threshold().default_value().value() == 0) {
+    throw EnvoyException("Success Rate Threshold cannot be zero percent");
+  }
+
   const std::string prefix = stats_prefix + "admission_control.";
 
   // Create the thread-local controller.

test/extensions/filters/http/admission_control/BUILD

@@ -37,6 +37,7 @@ envoy_extension_cc_test(
         "//source/common/http:header_map_lib",
         "//source/common/http:headers_lib",
         "//source/extensions/filters/http/admission_control:admission_control_filter_lib",
+        "//source/extensions/filters/http/admission_control:config",
         "//test/mocks/http:http_mocks",
         "//test/mocks/server:factory_context_mocks",
         "//test/mocks/thread_local:thread_local_mocks",

test/extensions/filters/http/admission_control/config_test.cc

@@ -6,6 +6,7 @@
 #include "common/stats/isolated_store_impl.h"
 
 #include "extensions/filters/http/admission_control/admission_control.h"
+#include "extensions/filters/http/admission_control/config.h"
 #include "extensions/filters/http/admission_control/evaluators/success_criteria_evaluator.h"
 
 #include "test/mocks/runtime/mocks.h"
@@ -46,6 +47,36 @@ class AdmissionControlConfigTest : public testing::Test {
   NiceMock<Random::MockRandomGenerator> random_;
 };
 
+// Ensure the filter ingest throws an exception if it is passed a config with a default value of 0
+// for sr_threshold If exception was not thrown, a default value of 0 for sr_threshold induces a
+// divide by zero error
+TEST_F(AdmissionControlConfigTest, ZeroSuccessRateThreshold) {
+  AdmissionControlFilterFactory admission_control_filter_factory;
+  const std::string yaml = R"EOF(
+enabled:
+  default_value: false
+  runtime_key: "foo.enabled"
+sampling_window: 1337s
+sr_threshold:
+  default_value:
+    value: 0
+  runtime_key: "foo.sr_threshold"
+aggression:
+  default_value: 4.2
+  runtime_key: "foo.aggression"
+success_criteria:
+  http_criteria:
+  grpc_criteria:
+)EOF";
+
+  AdmissionControlProto proto;
+  TestUtility::loadFromYamlAndValidate(yaml, proto);
+  NiceMock<Server::Configuration::MockFactoryContext> factory_context;
+  EXPECT_THROW_WITH_MESSAGE(admission_control_filter_factory.createFilterFactoryFromProtoTyped(
+                                proto, "whatever", factory_context),
+                            EnvoyException, "Success Rate Threshold cannot be zero percent");
+}
+
 // Verify the configuration when all fields are set.
 TEST_F(AdmissionControlConfigTest, BasicTestAllConfigured) {
   const std::string yaml = R"EOF(