virtio_console: fix sparse warnings

CHECK drivers/char/virtio_console.c
drivers/char/virtio_console.c:687:36: warning: incorrect type in
	argument 1 (different address spaces)
drivers/char/virtio_console.c:687:36:    expected void [noderef]
	<asn:1>*to
drivers/char/virtio_console.c:687:36:    got char *out_buf
drivers/char/virtio_console.c:790:35: warning: incorrect type in
	argument 2 (different address spaces)
drivers/char/virtio_console.c:790:35:    expected char *out_buf
drivers/char/virtio_console.c:790:35:    got char [noderef]
	<asn:1>*ubuf

fill_readbuf is reused with both kernel and userspace pointers,
depending on value of to_user flag.

Tag address parameter as __user, and cast to/from regular pointer type
when we know it's safe.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

1 files changed, 5 insertions, 4 deletions

diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
index 6cc832b45185..de03df9dd7c9 100644
--- a/drivers/char/virtio_console.c
+++ b/drivers/char/virtio_console.c
@@ -669,8 +669,8 @@ done:
  * Give out the data that's requested from the buffer that we have
  * queued up.
  */
-static ssize_t fill_readbuf(struct port *port, char *out_buf, size_t out_count,
-                            bool to_user)
+static ssize_t fill_readbuf(struct port *port, char __user *out_buf,
+                            size_t out_count, bool to_user)
 {
         struct port_buffer *buf;
         unsigned long flags;
@@ -688,7 +688,8 @@ static ssize_t fill_readbuf(struct port *port, char *out_buf, size_t out_count,
                 if (ret)
                         return -EFAULT;
         } else {
-                memcpy(out_buf, buf->buf + buf->offset, out_count);
+                memcpy((__force char *)out_buf, buf->buf + buf->offset,
+                       out_count);
         }
 
         buf->offset += out_count;
@@ -1162,7 +1163,7 @@ static int get_chars(u32 vtermno, char *buf, int count)
         /* If we don't have an input queue yet, we can't get input. */
         BUG_ON(!port->in_vq);
 
-        return fill_readbuf(port, buf, count, false);
+        return fill_readbuf(port, (__force char __user *)buf, count, false);
 }
 
 static void resize_console(struct port *port)