FAILED: patch "[PATCH] libceph: handle an empty authorize reply" failed to apply to 4.4-stable tree

[<gregkh@xxxxxxxxxxxxxxxxxxx>]

The patch below does not apply to the 4.4-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@xxxxxxxxxxxxxxx>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

>From 0fd3fd0a9bb0b02b6435bb7070e9f7b82a23f068 Mon Sep 17 00:00:00 2001
From: Ilya Dryomov <idryomov@xxxxxxxxx>
Date: Tue, 5 Feb 2019 20:30:27 +0100
Subject: [PATCH] libceph: handle an empty authorize reply

The authorize reply can be empty, for example when the ticket used to
build the authorizer is too old and TAG_BADAUTHORIZER is returned from
the service.  Calling ->verify_authorizer_reply() results in an attempt
to decrypt and validate (somewhat) random data in au->buf (most likely
the signature block from calc_signature()), which fails and ends up in
con_fault_finish() with !con->auth_retry.  The ticket isn't invalidated
and the connection is retried again and again until a new ticket is
obtained from the monitor:

  libceph: osd2 192.168.122.1:6809 bad authorize reply
  libceph: osd2 192.168.122.1:6809 bad authorize reply
  libceph: osd2 192.168.122.1:6809 bad authorize reply
  libceph: osd2 192.168.122.1:6809 bad authorize reply

Let TAG_BADAUTHORIZER handler kick in and increment con->auth_retry.

Cc: stable@xxxxxxxxxxxxxxx
Fixes: 5c056fdc5b47 ("libceph: verify authorize reply on connect")
Link: https://tracker.ceph.com/issues/20164
Signed-off-by: Ilya Dryomov <idryomov@xxxxxxxxx>
Reviewed-by: Sage Weil <sage@xxxxxxxxxx>

diff --git a/net/ceph/messenger.c b/net/ceph/messenger.c
index 3661cdd927f1..7e71b0df1fbc 100644
--- a/net/ceph/messenger.c
+++ b/net/ceph/messenger.c
@@ -2058,6 +2058,8 @@ static int process_connect(struct ceph_connection *con)
 	dout("process_connect on %p tag %d\n", con, (int)con->in_tag);
 
 	if (con->auth) {
+		int len = le32_to_cpu(con->in_reply.authorizer_len);
+
 		/*
 		 * Any connection that defines ->get_authorizer()
 		 * should also define ->add_authorizer_challenge() and
@@ -2067,8 +2069,7 @@ static int process_connect(struct ceph_connection *con)
 		 */
 		if (con->in_reply.tag == CEPH_MSGR_TAG_CHALLENGE_AUTHORIZER) {
 			ret = con->ops->add_authorizer_challenge(
-				    con, con->auth->authorizer_reply_buf,
-				    le32_to_cpu(con->in_reply.authorizer_len));
+				    con, con->auth->authorizer_reply_buf, len);
 			if (ret < 0)
 				return ret;
 
@@ -2078,10 +2079,12 @@ static int process_connect(struct ceph_connection *con)
 			return 0;
 		}
 
-		ret = con->ops->verify_authorizer_reply(con);
-		if (ret < 0) {
-			con->error_msg = "bad authorize reply";
-			return ret;
+		if (len) {
+			ret = con->ops->verify_authorizer_reply(con);
+			if (ret < 0) {
+				con->error_msg = "bad authorize reply";
+				return ret;
+			}
 		}
 	}