amdkfd: use calloc instead of kzalloc to avoid integer overflow

BugLink: https://bugs.launchpad.net/bugs/2065805

commit 3b0daecfeac0103aba8b293df07a0cbaf8b43f29 upstream.

This uses calloc instead of doing the multiplication which might
overflow.

Cc: stable@vger.kernel.org
Signed-off-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Manuel Diewald <manuel.diewald@canonical.com>
Signed-off-by: Roxana Nicolescu <roxana.nicolescu@canonical.com>

Author: airlied

drivers/gpu/drm/amd/amdkfd/kfd_chardev.c

@@ -940,8 +940,8 @@ static int kfd_ioctl_get_process_apertures_new(struct file *filp,
 	 * nodes, but not more than args->num_of_nodes as that is
 	 * the amount of memory allocated by user
 	 */
-	pa = kzalloc((sizeof(struct kfd_process_device_apertures) *
-				args->num_of_nodes), GFP_KERNEL);
+	pa = kcalloc(args->num_of_nodes, sizeof(struct kfd_process_device_apertures),
+		     GFP_KERNEL);
 	if (!pa)
 		return -ENOMEM;