From: Amit Shah Date: Mon, 29 Jul 2013 04:47:13 +0000 (+0930) Subject: virtio: console: fix race in port_fops_open() and port unplug X-Git-Tag: firefly_0821_release~6453^2~1096 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=60391483d53a0a9bb43e78a867173b92cf9da996;p=firefly-linux-kernel-4.4.55.git virtio: console: fix race in port_fops_open() and port unplug 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 Signed-off-by: Rusty Russell Signed-off-by: Greg Kroah-Hartman --- diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c index 3beea9d478bc..ffa7e46faff9 100644 --- a/drivers/char/virtio_console.c +++ b/drivers/char/virtio_console.c @@ -1041,6 +1041,10 @@ static int port_fops_open(struct inode *inode, struct file *filp) /* 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; /*