virtio_console: fix missing byte order handling for cols and rows

As per virtio spec the fields cols and rows are specified as little
endian. Although there is no legacy interface requirement that would
state that cols and rows need to be handled as native endian when legacy
interface is used, unlike for the fields of the adjacent struct
virtio_console_control, I decided to err on the side of caution based
on some non-conclusive virtio spec repo archaeology and opt for using
virtio16_to_cpu() much like for virtio_console_control.event. Strictly
by the letter of the spec virtio_le_to_cpu() would have been sufficient.
But when the legacy interface is not used, it boils down to the same.

And when using the legacy interface, the device formatting these as
little endian when the guest is big endian would surprise me more than
it using guest native byte order (which would make it compatible with
the current implementation). Nevertheless somebody trying to implement
the spec following it to the letter could end up forcing little endian
byte order when the legacy interface is in use. So IMHO this ultimately
needs a judgement call by the maintainers.

Fixes: 8345adbf96fc1 ("virtio: console: Accept console size along with resize control message")
Signed-off-by: Halil Pasic <pasic@linux.ibm.com>
Cc: stable@vger.kernel.org # v2.6.35+
Message-Id: <20250322002954.3129282-1-pasic@linux.ibm.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
index 5f04951d0dd469881ac393db1542d16db4cca262..216c5115637d39575754d6ec12e20cccc3262703 100644 (file)
--- a/drivers/char/virtio_console.c
+++ b/drivers/char/virtio_console.c
@@ -1576,8 +1576,8 @@ static void handle_control_message(struct virtio_device *vdev,
                break;
        case VIRTIO_CONSOLE_RESIZE: {
                struct {
-                       __u16 rows;
-                       __u16 cols;
+                       __virtio16 rows;
+                       __virtio16 cols;
                } size;
 
                if (!is_console_port(port))
@@ -1585,7 +1585,8 @@ static void handle_control_message(struct virtio_device *vdev,
 
                memcpy(&size, buf->buf + buf->offset + sizeof(*cpkt),
                       sizeof(size));
-               set_console_size(port, size.rows, size.cols);
+               set_console_size(port, virtio16_to_cpu(vdev, size.rows),
+                                virtio16_to_cpu(vdev, size.cols));
 
                port->cons.hvc->irq_requested = 1;
                resize_console(port);