Fix lock violations.

The locks should not be rewritten. This is especially confusing with locking
seemingly respected in the first part of this function. Instead, just update
the relevant fields while holding appropriate locks.

PiperOrigin-RevId: 492317437

pkg/tcpip/transport/internal/network/endpoint.go

@@ -118,10 +118,9 @@ type multicastMembership struct {
 // Init initializes the endpoint.
 func (e *Endpoint) Init(s *stack.Stack, netProto tcpip.NetworkProtocolNumber, transProto tcpip.TransportProtocolNumber, ops *tcpip.SocketOptions, waiterQueue *waiter.Queue) {
 	e.mu.Lock()
-	memberships := e.multicastMemberships
-	e.mu.Unlock()
-	if memberships != nil {
-		panic(fmt.Sprintf("endpoint is already initialized; got e.multicastMemberships = %#v, want = nil", memberships))
+	defer e.mu.Unlock()
+	if e.multicastMemberships != nil {
+		panic(fmt.Sprintf("endpoint is already initialized; got e.multicastMemberships = %#v, want = nil", e.multicastMemberships))
 	}
 
 	switch netProto {
@@ -130,27 +129,24 @@ func (e *Endpoint) Init(s *stack.Stack, netProto tcpip.NetworkProtocolNumber, tr
 		panic(fmt.Sprintf("invalid protocol number = %d", netProto))
 	}
 
-	*e = Endpoint{
-		stack:       s,
-		ops:         ops,
-		netProto:    netProto,
-		transProto:  transProto,
-		waiterQueue: waiterQueue,
-
-		info: stack.TransportEndpointInfo{
-			NetProto:   netProto,
-			TransProto: transProto,
-		},
-		effectiveNetProto: netProto,
-		ipv4TTL:           tcpip.UseDefaultIPv4TTL,
-		ipv6HopLimit:      tcpip.UseDefaultIPv6HopLimit,
-		// Linux defaults to TTL=1.
-		multicastTTL:         1,
-		multicastMemberships: make(map[multicastMembership]struct{}),
+	e.stack = s
+	e.ops = ops
+	e.netProto = netProto
+	e.transProto = transProto
+	e.waiterQueue = waiterQueue
+	e.infoMu.Lock()
+	e.info = stack.TransportEndpointInfo{
+		NetProto:   netProto,
+		TransProto: transProto,
 	}
+	e.infoMu.Unlock()
+	e.effectiveNetProto = netProto
+	e.ipv4TTL = tcpip.UseDefaultIPv4TTL
+	e.ipv6HopLimit = tcpip.UseDefaultIPv6HopLimit
 
-	e.mu.Lock()
-	defer e.mu.Unlock()
+	// Linux defaults to TTL=1.
+	e.multicastTTL = 1
+	e.multicastMemberships = make(map[multicastMembership]struct{})
 	e.setEndpointState(transport.DatagramEndpointStateInitial)
 }