[3.16.y-ckt stable] Patch "target: Don't call TFO->write_pending if data_length == 0" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    target: Don't call TFO->write_pending if data_length == 0

to the linux-3.16.y-queue branch of the 3.16.y-ckt extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.16.y-queue

This patch is scheduled to be released in version 3.16.7-ckt3.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.16.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From 508f914cb329c7f0e99bddf3cf0928bfecb669cf Mon Sep 17 00:00:00 2001
From: Roland Dreier <roland at purestorage.com>
Date: Tue, 14 Oct 2014 14:16:24 -0700
Subject: target: Don't call TFO->write_pending if data_length == 0

commit 885e7b0e181c14e4d0ddd26c688bad2b84c1ada9 upstream.

If an initiator sends a zero-length command (e.g. TEST UNIT READY) but
sets the transfer direction in the transport layer to indicate a
data-out phase, we still shouldn't try to transfer data.  At best it's
a NOP, and depending on the transport, we might crash on an
uninitialized sg list.

Reported-by: Craig Watson <craig.watson at vanguard-rugged.com>
Signed-off-by: Roland Dreier <roland at purestorage.com>
Signed-off-by: Nicholas Bellinger <nab at linux-iscsi.org>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/target/target_core_transport.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c
index ab610146681d..a9c77b5116e3 100644
--- a/drivers/target/target_core_transport.c
+++ b/drivers/target/target_core_transport.c
@@ -2295,7 +2295,7 @@ transport_generic_new_cmd(struct se_cmd *cmd)
 	 * and let it call back once the write buffers are ready.
 	 */
 	target_add_to_state_list(cmd);
-	if (cmd->data_direction != DMA_TO_DEVICE) {
+	if (cmd->data_direction != DMA_TO_DEVICE || cmd->data_length == 0) {
 		target_execute_cmd(cmd);
 		return 0;
 	}
--
2.1.0