Handle zero time correctly in gonet.deadlineTimer.

After setDeadline(ch, timer, time.Time{}), the timer pointer is not reset and
may point to an already expired timer. So the next call to setDeadline() will
close the cancel channel, even though the timer did not expire. This was fixed
by setting timer to nil if time.Time.IsZero().

Fixes #9885

Co-authored-by: snyh <snyh@snyh.org>
PiperOrigin-RevId: 598940274

pkg/tcpip/adapters/gonet/BUILD

@@ -25,6 +25,7 @@ go_test(
     srcs = ["gonet_test.go"],
     library = ":gonet",
     deps = [
+        "//pkg/sync",
         "//pkg/tcpip",
         "//pkg/tcpip/header",
         "//pkg/tcpip/link/loopback",

pkg/tcpip/adapters/gonet/gonet.go

@@ -179,6 +179,7 @@ func (d *deadlineTimer) setDeadline(cancelCh *chan struct{}, timer **time.Timer,
 	// "A zero value for t means I/O operations will not time out."
 	// - net.Conn.SetDeadline
 	if t.IsZero() {
+		*timer = nil
 		return
 	}
 

pkg/tcpip/adapters/gonet/gonet_test.go

@@ -25,6 +25,7 @@ import (
 	"time"
 
 	"golang.org/x/net/nettest"
+	"gvisor.dev/gvisor/pkg/sync"
 	"gvisor.dev/gvisor/pkg/tcpip"
 	"gvisor.dev/gvisor/pkg/tcpip/header"
 	"gvisor.dev/gvisor/pkg/tcpip/link/loopback"
@@ -1003,3 +1004,25 @@ func TestInterruptListender(t *testing.T) {
 func TestNetTest(t *testing.T) {
 	nettest.TestConn(t, makePipe)
 }
+
+// NOTE(gvisor.dev/issue/9885): Regression test.
+func TestDeadlineTimerAfterZeroValue(t *testing.T) {
+	timer := &deadlineTimer{}
+	timer.init()
+
+	wg := sync.WaitGroup{}
+	ch := timer.readCancel()
+	wg.Add(1)
+	go func() {
+		defer wg.Done()
+		select {
+		case <-ch:
+		case <-time.After(1 * time.Second):
+			t.Fail()
+		}
+	}()
+	timer.SetReadDeadline(time.Now().Add(10 * time.Second))
+	timer.SetReadDeadline(time.Time{})
+	timer.SetReadDeadline(time.Unix(1, 0))
+	wg.Wait()
+}