virtio: console: Don't access vqs if device was unplugged

PATCH New Rusty Russell 1 participant 1 message Mar 4, 2011

Subsystems (3)

Char and misc drivers virtio core virtio console driver

lore

Share & tools

lore

Rusty Russell

author

2011-03-04 03:34 UTC #0 lore raw

PATCH 1/1 virtio: console: Don't access vqs if device was unplugged

From: Amit Shah <[email protected]>

If a virtio-console device gets unplugged while a port is open, a subsequent close() call on the port accesses vqs to free up buffers. This can lead to a crash.

The buffers are already freed up as a result of the call to unplug_ports() from virtcons_remove(). The fix is to simply not access vq information if port->portdev is NULL.

Reported-by juzhang <[email protected]>

CC [email protected]

Signed-off-by Amit Shah <[email protected]>

Signed-off-by Rusty Russell <[email protected]>

---
 drivers/char/virtio_console.c |    8 ++++++++
 1 file changed, 8 insertions(+)

drivers/char/virtio_console.c +8 -0

index 4903931..84b164d 100644
@@ -388,6 +388,10 @@ static void discard_port_data(struct port *port)
 	unsigned int len;
 	int ret;
 
+	if (!port->portdev) {
+		/* Device has been unplugged.  vqs are already gone. */
+		return;
+	}
 	vq = port->in_vq;
 	if (port->inbuf)
 		buf = port->inbuf;

@@ -470,6 +474,10 @@ static void reclaim_consumed_buffers(struct port *port)
 	void *buf;
 	unsigned int len;
 
+	if (!port->portdev) {
+		/* Device has been unplugged.  vqs are already gone. */
+		return;
+	}
 	while ((buf = virtqueue_get_buf(port->out_vq, &len))) {
 		kfree(buf);
 		port->outvq_full = false;