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 3.4-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-3.4 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
@@ -794,6 +794,10 @@ 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-3.4/virtio-console-fix-raising-sigio-after-port-unplug.patch
queue-3.4/virtio-console-clean-up-port-data-immediately-at-time-of-unplug.patch
queue-3.4/virtio-console-fix-race-in-port_fops_open-and-port-unplug.patch
queue-3.4/virtio-console-return-enodev-on-all-read-operations-after-unplug.patch
queue-3.4/virtio-console-fix-race-with-port-unplug-and-open-close.patch
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