staging: fbtft: Use kmalloc_array

Use kmalloc_array instead of kmalloc for arrays to prevent integer
overflows.
This was done using Coccinelle:

@@
expression e1, e2;
constant C;
type t;
@@
(
- kmalloc(
+ kmalloc_array(
e2
- *
+ ,
sizeof(e1), C)
|
- kmalloc(
+ kmalloc_array(
e1
- *
+ ,
sizeof(t), C)
|
- kmalloc(
+ kmalloc_array(
- sizeof(e1)
- *
e2
+ ,
+ sizeof(e1)
, C)
|
- kmalloc(
+ kmalloc_array(
- sizeof(t)
- *
e1
+ ,
+ sizeof(t)
, C)
)

Signed-off-by: Bhaktipriya Shridhar <bhaktipriya96@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/fbtft/fb_agm1264k-fl.c

@@ -272,8 +272,8 @@ static int write_vmem(struct fbtft_par *par, size_t offset, size_t len)
 	int ret = 0;
 
 	/* buffer to convert RGB565 -> grayscale16 -> Dithered image 1bpp */
-	signed short *convert_buf = kmalloc(par->info->var.xres *
-		par->info->var.yres * sizeof(signed short), GFP_NOIO);
+	signed short *convert_buf = kmalloc_array(par->info->var.xres *
+		par->info->var.yres, sizeof(signed short), GFP_NOIO);
 
 	if (!convert_buf)
 		return -ENOMEM;