From 69df425318e053ccb7e4dc4d5fb2c5594c7928c0 Mon Sep 17 00:00:00 2001
From: Marten Seemann <martenseemann@gmail.com>
Date: Tue, 11 Aug 2020 10:44:24 +0700
Subject: [PATCH] limit Config.MaxIncoming{Uni}Streams to 2^60

---
 client.go      |  3 +++
 config.go      | 19 ++++++++++++++++++-
 config_test.go | 18 ++++++++++++++++++
 interface.go   |  2 ++
 server.go      |  3 +++
 5 files changed, 44 insertions(+), 1 deletion(-)

diff --git a/client.go b/client.go
index 63db2cdb..e77a788f 100644
--- a/client.go
+++ b/client.go
@@ -164,6 +164,9 @@ func dialContext(
 	if tlsConf == nil {
 		return nil, errors.New("quic: tls.Config not set")
 	}
+	if err := validateConfig(config); err != nil {
+		return nil, err
+	}
 	config = populateClientConfig(config, createdPacketConn)
 	packetHandlers, err := getMultiplexer().AddConn(pconn, config.ConnectionIDLength, config.StatelessResetKey, config.Tracer)
 	if err != nil {
diff --git a/config.go b/config.go
index 1790bbb1..a8c308db 100644
--- a/config.go
+++ b/config.go
@@ -1,6 +1,10 @@
 package quic
 
-import "github.com/lucas-clemente/quic-go/internal/protocol"
+import (
+	"errors"
+
+	"github.com/lucas-clemente/quic-go/internal/protocol"
+)
 
 // Clone clones a Config
 func (c *Config) Clone() *Config {
@@ -8,6 +12,19 @@ func (c *Config) Clone() *Config {
 	return &copy
 }
 
+func validateConfig(config *Config) error {
+	if config == nil {
+		return nil
+	}
+	if config.MaxIncomingStreams > 1<<60 {
+		return errors.New("invalid value for Config.MaxIncomingStreams")
+	}
+	if config.MaxIncomingUniStreams > 1<<60 {
+		return errors.New("invalid value for Config.MaxIncomingUniStreams")
+	}
+	return nil
+}
+
 // populateServerConfig populates fields in the quic.Config with their default values, if none are set
 // it may be called with nil
 func populateServerConfig(config *Config) *Config {
diff --git a/config_test.go b/config_test.go
index d96fcf80..ad9b23c7 100644
--- a/config_test.go
+++ b/config_test.go
@@ -15,6 +15,24 @@ import (
 )
 
 var _ = Describe("Config", func() {
+	Context("validating", func() {
+		It("validates a nil config", func() {
+			Expect(validateConfig(nil)).To(Succeed())
+		})
+
+		It("validates a config with normal values", func() {
+			Expect(validateConfig(populateServerConfig(&Config{}))).To(Succeed())
+		})
+
+		It("errors on too large values for MaxIncomingStreams", func() {
+			Expect(validateConfig(&Config{MaxIncomingStreams: 1<<60 + 1})).To(MatchError("invalid value for Config.MaxIncomingStreams"))
+		})
+
+		It("errors on too large values for MaxIncomingUniStreams", func() {
+			Expect(validateConfig(&Config{MaxIncomingUniStreams: 1<<60 + 1})).To(MatchError("invalid value for Config.MaxIncomingUniStreams"))
+		})
+	})
+
 	configWithNonZeroNonFunctionFields := func() *Config {
 		c := &Config{}
 		v := reflect.ValueOf(c).Elem()
diff --git a/interface.go b/interface.go
index 9229b216..bb825542 100644
--- a/interface.go
+++ b/interface.go
@@ -242,10 +242,12 @@ type Config struct {
 	// If this value is zero, it will default to 1.5 MB for the server and 15 MB for the client.
 	MaxReceiveConnectionFlowControlWindow uint64
 	// MaxIncomingStreams is the maximum number of concurrent bidirectional streams that a peer is allowed to open.
+	// Values above 2^60 are invalid.
 	// If not set, it will default to 100.
 	// If set to a negative value, it doesn't allow any bidirectional streams.
 	MaxIncomingStreams int64
 	// MaxIncomingUniStreams is the maximum number of concurrent unidirectional streams that a peer is allowed to open.
+	// Values above 2^60 are invalid.
 	// If not set, it will default to 100.
 	// If set to a negative value, it doesn't allow any unidirectional streams.
 	MaxIncomingUniStreams int64
diff --git a/server.go b/server.go
index c4fa4291..6766f2f4 100644
--- a/server.go
+++ b/server.go
@@ -171,6 +171,9 @@ func listen(conn net.PacketConn, tlsConf *tls.Config, config *Config, acceptEarl
 	if tlsConf == nil {
 		return nil, errors.New("quic: tls.Config not set")
 	}
+	if err := validateConfig(config); err != nil {
+		return nil, err
+	}
 	config = populateServerConfig(config)
 	for _, v := range config.Versions {
 		if !protocol.IsValidVersion(v) {