icmp: don't step on recycled socket descriptors
This change fixes lazy socket descriptor handling in ListenPacket to
avoid treading on someone's socket descriptors which are recycled by
descriptor duplication. The issue happens when calling ListenPacket for
non-privileged ICMP endpoint concurrently.
Fixes golang/go#16969.
Change-Id: I4d7672535f5aeb2a0b71f8af2c7ba271a085f418
Reviewed-on: https://go-review.googlesource.com/28473
Run-TryBot: Mikio Hara <mikioh.mikioh@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
diff --git a/icmp/listen_posix.go b/icmp/listen_posix.go
index b9f2607..7fac4f9 100644
--- a/icmp/listen_posix.go
+++ b/icmp/listen_posix.go
@@ -65,22 +65,24 @@
if err != nil {
return nil, os.NewSyscallError("socket", err)
}
- defer syscall.Close(s)
if runtime.GOOS == "darwin" && family == syscall.AF_INET {
if err := syscall.SetsockoptInt(s, iana.ProtocolIP, sysIP_STRIPHDR, 1); err != nil {
+ syscall.Close(s)
return nil, os.NewSyscallError("setsockopt", err)
}
}
sa, err := sockaddr(family, address)
if err != nil {
+ syscall.Close(s)
return nil, err
}
if err := syscall.Bind(s, sa); err != nil {
+ syscall.Close(s)
return nil, os.NewSyscallError("bind", err)
}
f := os.NewFile(uintptr(s), "datagram-oriented icmp")
- defer f.Close()
c, cerr = net.FilePacketConn(f)
+ f.Close()
default:
c, cerr = net.ListenPacket(network, address)
}
diff --git a/icmp/ping_test.go b/icmp/ping_test.go
index 4ec2692..3171dad 100644
--- a/icmp/ping_test.go
+++ b/icmp/ping_test.go
@@ -10,6 +10,7 @@
"net"
"os"
"runtime"
+ "sync"
"testing"
"time"
@@ -164,3 +165,36 @@
return fmt.Errorf("got %+v from %v; want echo reply", rm, peer)
}
}
+
+func TestConcurrentNonPrivilegedListenPacket(t *testing.T) {
+ if testing.Short() {
+ t.Skip("avoid external network")
+ }
+ switch runtime.GOOS {
+ case "darwin":
+ case "linux":
+ t.Log("you may need to adjust the net.ipv4.ping_group_range kernel state")
+ default:
+ t.Skipf("not supported on %s", runtime.GOOS)
+ }
+
+ network, address := "udp4", "127.0.0.1"
+ if !nettest.SupportsIPv4() {
+ network, address = "udp6", "::1"
+ }
+ const N = 1000
+ var wg sync.WaitGroup
+ wg.Add(N)
+ for i := 0; i < N; i++ {
+ go func() {
+ defer wg.Done()
+ c, err := icmp.ListenPacket(network, address)
+ if err != nil {
+ t.Error(err)
+ return
+ }
+ c.Close()
+ }()
+ }
+ wg.Wait()
+}
