Use array_size to protect against multiplication overflows.

The changes were done using the following Coccinelle semantic patch:

// <smpl>
@@
    size_t e1,e2;
    expression COUNT;
    identifier alloc = {vmalloc,vzalloc,kvmalloc,kvzalloc};
@@

(
      alloc(
-           (e1) * (e2)
+           array_size(e1, e2)
      ,...)
|
      alloc(
-           (e1) * (COUNT)
+           array_size(COUNT, e1)
      ,...)
)
// </smpl>

Signed-off-by: Julia Lawall <Julia.Lawall@inria.fr>

---
 drivers/comedi/comedi_buf.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/comedi/comedi_buf.c b/drivers/comedi/comedi_buf.c
index 393966c09740..32ad3e6e1ce8 100644
--- a/drivers/comedi/comedi_buf.c
+++ b/drivers/comedi/comedi_buf.c
@@ -89,7 +89,7 @@ comedi_buf_map_alloc(struct comedi_device *dev, enum dma_data_direction dma_dir,
 		bm->dma_hw_dev = get_device(dev->hw_dev);
 	}
 
-	bm->page_list = vzalloc(sizeof(*buf) * n_pages);
+	bm->page_list = vzalloc(array_size(n_pages, sizeof(*buf)));
 	if (!bm->page_list)
 		goto err;
 
@@ -169,7 +169,7 @@ static void __comedi_buf_alloc(struct comedi_device *dev,
 		buf = &bm->page_list[0];
 		async->prealloc_buf = buf->virt_addr;
 	} else {
-		pages = vmalloc(sizeof(struct page *) * n_pages);
+		pages = vmalloc(array_size(n_pages, sizeof(struct page *)));
 		if (!pages)
 			return;