From 3c230a0fc456bd6ef3f5d2a5f398bd3445f2e1e9 Mon Sep 17 00:00:00 2001
From: Jeroen van Erp <jeroen@hierynomus.com>
Date: Fri, 18 Mar 2016 13:11:59 +0100
Subject: [PATCH] Fixed potential race condition identified in #203

---
 .../sshj/connection/channel/ChannelInputStream.java      | 9 +++++++--
 1 file changed, 7 insertions(+), 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
index 76150fed..4205fd21 100644
--- 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 final class ChannelInputStream
             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 final class ChannelInputStream
         return "< ChannelInputStream for Channel #" + chan.getID() + " >";
     }
 
-}
\ No newline at end of file
+}