upstream: cap channel input buffer size at 16MB; avoids high memory use

when peer advertises a large window but is slow to consume the data we send
(e.g. because of a slow network)

reported by Pierre-Yves David

fix with & ok markus@

OpenBSD-Commit-ID: 1452771f5e5e768876d3bfe2544e3866d6ade216

1 files changed, 4 insertions, 1 deletions

diff --git a/channels.h b/channels.h
index ee818880e..74e9b3f87 100644
--- a/channels.h
+++ b/channels.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: channels.h,v 1.134 2020/07/05 23:59:45 djm Exp $ */
+/* $OpenBSD: channels.h,v 1.135 2020/09/20 05:47:25 djm Exp $ */
 
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
@@ -223,6 +223,9 @@ struct Channel {
 /* Read buffer size */
 #define CHAN_RBUF       (16*1024)
 
+/* Maximum channel input buffer size */
+#define CHAN_INPUT_MAX  (16*1024*1024)
+
 /* Hard limit on number of channels */
 #define CHANNELS_MAX_CHANNELS   (16*1024)