virtio: console: fix race in port_fops_open() and port unplug
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.
CC: <stable@vger.kernel.org>
Signed-off-by: Amit Shah <amit.shah@redhat.com>
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 @@
/* 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;
/*
