Fixed potential race condition identified in #203

hierynomus · Mar 18, 2016 · 3c230a0 · 3c230a0
1 parent 4f15274
commit 3c230a0
Showing 1 changed file with 7 additions and 2 deletions.
diff --git a/src/main/java/net/schmizz/sshj/connection/channel/ChannelInputStream.java b/src/main/java/net/schmizz/sshj/connection/channel/ChannelInputStream.java
@@ -130,7 +130,12 @@ public void receive(byte[] data, int offset, int len)
             buf.putRawBytes(data, offset, len);
             buf.notifyAll();
         }
-        win.consume(len);
+        // Potential fix for #203 (window consumed below 0).
+        // This seems to be a race condition if we receive more data, while we're already sending a SSH_MSG_CHANNEL_WINDOW_ADJUST
+        // And the window has not expanded yet.
+        synchronized (win) {
+            win.consume(len);
+        }
         if (chan.getAutoExpand())
             checkWindow();
     }
@@ -153,4 +158,4 @@ public String toString() {
         return "< ChannelInputStream for Channel #" + chan.getID() + " >";
     }
 
-}
+}