ssh: fix deadlock during error path
Fixes golang/go#11882
If an error occurs during handshakeTransport.writePacket the lock may not be
released. Fix this by using defer rather than manually unlocking in all paths.
Change-Id: I0010284b4f7d99907c86b4c0e140ab6cf37b0441
Reviewed-on: https://go-review.googlesource.com/12888
Reviewed-by: Adam Langley <agl@golang.org>
diff --git a/ssh/handshake.go b/ssh/handshake.go
index a1e2c23..4acc1a0 100644
--- a/ssh/handshake.go
+++ b/ssh/handshake.go
@@ -253,6 +253,8 @@
func (t *handshakeTransport) writePacket(p []byte) error {
t.mu.Lock()
+ defer t.mu.Unlock()
+
if t.writtenSinceKex > t.config.RekeyThreshold {
t.sendKexInitLocked()
}
@@ -264,17 +266,14 @@
}
t.writtenSinceKex += uint64(len(p))
- var err error
switch p[0] {
case msgKexInit:
- err = errors.New("ssh: only handshakeTransport can send kexInit")
+ return errors.New("ssh: only handshakeTransport can send kexInit")
case msgNewKeys:
- err = errors.New("ssh: only handshakeTransport can send newKeys")
+ return errors.New("ssh: only handshakeTransport can send newKeys")
default:
- err = t.conn.writePacket(p)
+ return t.conn.writePacket(p)
}
- t.mu.Unlock()
- return err
}
func (t *handshakeTransport) Close() error {
