virtio-console: Check if chardev backends available before calling into them

For the callback functions invoked by the virtio-serial-bus code, check
if we have chardev backends registered before we call into the chardev
functions.

Signed-off-by: Amit Shah <amit.shah@redhat.com>
Reported-by: Anthony Liguori <aliguori@us.ibm.com>
Signed-off-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

1 files changed, 11 insertions, 0 deletions

diff --git a/hw/virtio-console.c b/hw/virtio-console.c
index d3351c83f..dbbea76df 100644
--- a/hw/virtio-console.c
+++ b/hw/virtio-console.c
@@ -27,6 +27,11 @@ static ssize_t flush_buf(VirtIOSerialPort *port, const uint8_t *buf, size_t len)
     VirtConsole *vcon = DO_UPCAST(VirtConsole, port, port);
     ssize_t ret;
 
+    if (!vcon->chr) {
+        /* If there's no backend, we can just say we consumed all data. */
+        return len;
+    }
+
     ret = qemu_chr_fe_write(vcon->chr, buf, len);
     trace_virtio_console_flush_buf(port->id, len, ret);
 
@@ -52,6 +57,9 @@ static void guest_open(VirtIOSerialPort *port)
 {
     VirtConsole *vcon = DO_UPCAST(VirtConsole, port, port);
 
+    if (!vcon->chr) {
+        return;
+    }
     qemu_chr_fe_open(vcon->chr);
 }
 
@@ -60,6 +68,9 @@ static void guest_close(VirtIOSerialPort *port)
 {
     VirtConsole *vcon = DO_UPCAST(VirtConsole, port, port);
 
+    if (!vcon->chr) {
+        return;
+    }
     qemu_chr_fe_close(vcon->chr);
 }