drm/gud: use vmalloc_array and vcalloc

Use vmalloc_array and vcalloc to protect against
multiplication overflows.

The changes were done using the following Coccinelle
semantic patch:

// <smpl>
@initialize:ocaml@
@@

let rename alloc =
  match alloc with
    "vmalloc" -> "vmalloc_array"
  | "vzalloc" -> "vcalloc"
  | _ -> failwith "unknown"

@@
    size_t e1,e2;
    constant C1, C2;
    expression E1, E2, COUNT, x1, x2, x3;
    typedef u8;
    typedef __u8;
    type t = {u8,__u8,char,unsigned char};
    identifier alloc = {vmalloc,vzalloc};
    fresh identifier realloc = script:ocaml(alloc) { rename alloc };
@@

(
      alloc(x1*x2*x3)
|
      alloc(C1 * C2)
|
      alloc((sizeof(t)) * (COUNT), ...)
|
-     alloc((e1) * (e2))
+     realloc(e1, e2)
|
-     alloc((e1) * (COUNT))
+     realloc(COUNT, e1)
|
-     alloc((E1) * (E2))
+     realloc(E1, E2)
)
// </smpl>
Signed-off-by: Julia Lawall <Julia.Lawall@inria.fr>
Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de>
Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20230627144339.144478-4-Julia.Lawall@inria.fr

drivers/gpu/drm/gud/gud_pipe.c

@@ -390,7 +390,7 @@ static int gud_fb_queue_damage(struct gud_device *gdrm, struct drm_framebuffer *
 	mutex_lock(&gdrm->damage_lock);
 
 	if (!gdrm->shadow_buf) {
-		gdrm->shadow_buf = vzalloc(fb->pitches[0] * fb->height);
+		gdrm->shadow_buf = vcalloc(fb->pitches[0], fb->height);
 		if (!gdrm->shadow_buf) {
 			mutex_unlock(&gdrm->damage_lock);
 			return -ENOMEM;