patch "Drivers: hv: vmbus: Prevent sending data on a rescinded channel" added to char-misc-testing

patch "Drivers: hv: vmbus: Prevent sending data on a rescinded channel" added to char-misc-testing

[gregkh]

This is a note to let you know that I've just added the patch titled

    Drivers: hv: vmbus: Prevent sending data on a rescinded channel

to my char-misc git tree which can be found at
    git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc.git
in the char-misc-testing branch.

The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)

The patch will be merged to the char-misc-next branch sometime soon,
after it passes testing, and the merge window is open.

If you have any questions about this process, please let me know.


>From 932ed7be96752d2b6acfc62e494f9a6869993b80 Mon Sep 17 00:00:00 2001
From: "K. Y. Srinivasan" <kys@microsoft.com>
Date: Wed, 7 Dec 2016 01:16:28 -0800
Subject: Drivers: hv: vmbus: Prevent sending data on a rescinded channel

After the channel is rescinded, the host does not read from the rescinded channel.
Fail writes to a channel that has already been rescinded. If we permit writes on a
rescinded channel, since the host will not respond we will have situations where
we will be unable to unload vmbus drivers that cannot have any outstanding requests
to the host at the point they are unoaded.

Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Cc: <Stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/hv/ring_buffer.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/hv/ring_buffer.c b/drivers/hv/ring_buffer.c
index cd49cb17eb7f..2cd402986858 100644
--- a/drivers/hv/ring_buffer.c
+++ b/drivers/hv/ring_buffer.c
@@ -298,6 +298,9 @@ int hv_ringbuffer_write(struct vmbus_channel *channel,
 	unsigned long flags = 0;
 	struct hv_ring_buffer_info *outring_info = &channel->outbound;
 
+	if (channel->rescind)
+		return -ENODEV;
+
 	for (i = 0; i < kv_count; i++)
 		totalbytes_towrite += kv_list[i].iov_len;
 
@@ -350,6 +353,10 @@ int hv_ringbuffer_write(struct vmbus_channel *channel,
 		spin_unlock_irqrestore(&outring_info->ring_lock, flags);
 
 	hv_signal_on_write(old_write, channel, kick_q);
+
+	if (channel->rescind)
+		return -ENODEV;
+
 	return 0;
 }
 
-- 
2.11.0