From 4c25efc1f8e6b9d64bec94fe095a6f058112af2b Mon Sep 17 00:00:00 2001
From: Sahdev Zala <spzala@us.ibm.com>
Date: Mon, 10 Feb 2020 13:43:41 -0500
Subject: [PATCH] Discovery: do not allow passing negative cluster size
 (#11608)

When an etcd instance attempts to perform service discovery, if a
cluster size with negative value  is provided, the etcd instance
will panic without recovery because of
---
 etcdserver/api/v2discovery/discovery.go      | 22 ++++++++++----------
 etcdserver/api/v2discovery/discovery_test.go |  6 +++---
 2 files changed, 14 insertions(+), 14 deletions(-)

diff --git a/etcdserver/api/v2discovery/discovery.go b/etcdserver/api/v2discovery/discovery.go
index cf770b378..16ccfde8e 100644
--- a/etcdserver/api/v2discovery/discovery.go
+++ b/etcdserver/api/v2discovery/discovery.go
@@ -218,7 +218,7 @@ func (d *discovery) createSelf(contents string) error {
 	return err
 }
 
-func (d *discovery) checkCluster() ([]*client.Node, int, uint64, error) {
+func (d *discovery) checkCluster() ([]*client.Node, uint64, uint64, error) {
 	configKey := path.Join("/", d.cluster, "_config")
 	ctx, cancel := context.WithTimeout(context.Background(), client.DefaultRequestTimeout)
 	// find cluster size
@@ -247,7 +247,7 @@ func (d *discovery) checkCluster() ([]*client.Node, int, uint64, error) {
 		}
 		return nil, 0, 0, err
 	}
-	size, err := strconv.Atoi(resp.Node.Value)
+	size, err := strconv.ParseUint(resp.Node.Value, 10, 0)
 	if err != nil {
 		return nil, 0, 0, ErrBadSizeKey
 	}
@@ -288,7 +288,7 @@ func (d *discovery) checkCluster() ([]*client.Node, int, uint64, error) {
 		if path.Base(nodes[i].Key) == path.Base(d.selfKey()) {
 			break
 		}
-		if i >= size-1 {
+		if uint64(i) >= size-1 {
 			return nodes[:size], size, resp.Index, ErrFullCluster
 		}
 	}
@@ -316,7 +316,7 @@ func (d *discovery) logAndBackoffForRetry(step string) {
 	d.clock.Sleep(retryTimeInSecond)
 }
 
-func (d *discovery) checkClusterRetry() ([]*client.Node, int, uint64, error) {
+func (d *discovery) checkClusterRetry() ([]*client.Node, uint64, uint64, error) {
 	if d.retries < nRetries {
 		d.logAndBackoffForRetry("cluster status check")
 		return d.checkCluster()
@@ -336,8 +336,8 @@ func (d *discovery) waitNodesRetry() ([]*client.Node, error) {
 	return nil, ErrTooManyRetries
 }
 
-func (d *discovery) waitNodes(nodes []*client.Node, size int, index uint64) ([]*client.Node, error) {
-	if len(nodes) > size {
+func (d *discovery) waitNodes(nodes []*client.Node, size uint64, index uint64) ([]*client.Node, error) {
+	if uint64(len(nodes)) > size {
 		nodes = nodes[:size]
 	}
 	// watch from the next index
@@ -369,16 +369,16 @@ func (d *discovery) waitNodes(nodes []*client.Node, size int, index uint64) ([]*
 	}
 
 	// wait for others
-	for len(all) < size {
+	for uint64(len(all)) < size {
 		if d.lg != nil {
 			d.lg.Info(
 				"found peers from discovery server; waiting for more",
 				zap.String("discovery-url", d.url.String()),
 				zap.Int("found-peers", len(all)),
-				zap.Int("needed-peers", size-len(all)),
+				zap.Int("needed-peers", int(size-uint64(len(all)))),
 			)
 		} else {
-			plog.Noticef("found %d peer(s), waiting for %d more", len(all), size-len(all))
+			plog.Noticef("found %d peer(s), waiting for %d more", len(all), size-uint64(len(all)))
 		}
 		resp, err := w.Next(context.Background())
 		if err != nil {
@@ -415,7 +415,7 @@ func (d *discovery) selfKey() string {
 	return path.Join("/", d.cluster, d.id.String())
 }
 
-func nodesToCluster(ns []*client.Node, size int) (string, error) {
+func nodesToCluster(ns []*client.Node, size uint64) (string, error) {
 	s := make([]string, len(ns))
 	for i, n := range ns {
 		s[i] = n.Value
@@ -425,7 +425,7 @@ func nodesToCluster(ns []*client.Node, size int) (string, error) {
 	if err != nil {
 		return us, ErrInvalidURL
 	}
-	if m.Len() != size {
+	if uint64(m.Len()) != size {
 		return us, ErrDuplicateName
 	}
 	return us, nil
diff --git a/etcdserver/api/v2discovery/discovery_test.go b/etcdserver/api/v2discovery/discovery_test.go
index c1eff8823..939a26c4b 100644
--- a/etcdserver/api/v2discovery/discovery_test.go
+++ b/etcdserver/api/v2discovery/discovery_test.go
@@ -217,7 +217,7 @@ func TestCheckCluster(t *testing.T) {
 			if reflect.DeepEqual(ns, tt.nodes) {
 				t.Errorf("#%d: nodes = %v, want %v", i, ns, tt.nodes)
 			}
-			if size != tt.wsize {
+			if size != uint64(tt.wsize) {
 				t.Errorf("#%d: size = %v, want %d", i, size, tt.wsize)
 			}
 			if index != tt.index {
@@ -301,7 +301,7 @@ func TestWaitNodes(t *testing.T) {
 					fc.Advance(time.Second * (0x1 << i))
 				}
 			}()
-			g, err := d.waitNodes(tt.nodes, 3, 0) // we do not care about index in this test
+			g, err := d.waitNodes(tt.nodes, uint64(3), 0) // we do not care about index in this test
 			if err != nil {
 				t.Errorf("#%d: err = %v, want %v", i, err, nil)
 			}
@@ -348,7 +348,7 @@ func TestCreateSelf(t *testing.T) {
 func TestNodesToCluster(t *testing.T) {
 	tests := []struct {
 		nodes    []*client.Node
-		size     int
+		size     uint64
 		wcluster string
 		werr     error
 	}{