Patch "virtio: console: fix race in port_fops_open() and port unplug" has been added to the 3.10-stable tree

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

    virtio: console: fix race in port_fops_open() and port unplug

to the 3.10-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     virtio-console-fix-race-in-port_fops_open-and-port-unplug.patch
and it can be found in the queue-3.10 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.


>From 671bdea2b9f210566610603ecbb6584c8a201c8c Mon Sep 17 00:00:00 2001
From: Amit Shah <amit.shah@xxxxxxxxxx>
Date: Mon, 29 Jul 2013 14:17:13 +0930
Subject: virtio: console: fix race in port_fops_open() and port unplug

From: Amit Shah <amit.shah@xxxxxxxxxx>

commit 671bdea2b9f210566610603ecbb6584c8a201c8c upstream.

Between open() being called and processed, the port can be unplugged.
Check if this happened, and bail out.

A simple test script to reproduce this is:

while true; do for i in $(seq 1 100); do echo $i > /dev/vport0p3; done; done;

This opens and closes the port a lot of times; unplugging the port while
this is happening triggers the bug.

Signed-off-by: Amit Shah <amit.shah@xxxxxxxxxx>
Signed-off-by: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/char/virtio_console.c |    4 ++++
 1 file changed, 4 insertions(+)

--- a/drivers/char/virtio_console.c
+++ b/drivers/char/virtio_console.c
@@ -1041,6 +1041,10 @@ static int port_fops_open(struct inode *
 
 	/* We get the port with a kref here */
 	port = find_port_by_devt(cdev->dev);
+	if (!port) {
+		/* Port was unplugged before we could proceed */
+		return -ENXIO;
+	}
 	filp->private_data = port;
 
 	/*


Patches currently in stable-queue which might be from amit.shah@xxxxxxxxxx are

queue-3.10/virtio-console-fix-raising-sigio-after-port-unplug.patch
queue-3.10/virtio-console-clean-up-port-data-immediately-at-time-of-unplug.patch
queue-3.10/virtio-console-quit-from-splice_write-if-pipe-nrbufs-is-0.patch
queue-3.10/virtio-console-fix-race-in-port_fops_open-and-port-unplug.patch
queue-3.10/virtio-console-add-pipe_lock-unlock-for-splice_write.patch
queue-3.10/virtio-console-return-enodev-on-all-read-operations-after-unplug.patch
queue-3.10/virtio-console-fix-race-with-port-unplug-and-open-close.patch
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