From mboxrd@z Thu Jan 1 00:00:00 1970 From: Amit Shah Subject: [PATCH v2 02/11] virtio: console: fix race in port_fops_open() and port unplug Date: Fri, 19 Jul 2013 16:51:55 +0530 Message-ID: <18b14516fa1badb08dbfc3e892080b27127ff00f.1374232738.git.amit.shah@redhat.com> References: Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: In-Reply-To: References: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: virtualization-bounces@lists.linux-foundation.org Errors-To: virtualization-bounces@lists.linux-foundation.org To: Virtualization List Cc: Amit Shah , stable@vger.kernel.org List-Id: virtualization@lists.linuxfoundation.org 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 race condition. CC: Signed-off-by: Amit Shah --- drivers/char/virtio_console.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c index 291f437..b04ec95 100644 --- a/drivers/char/virtio_console.c +++ b/drivers/char/virtio_console.c @@ -1024,6 +1024,10 @@ 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; /* -- 1.8.1.4