drm/amdkfd: check kfd->ih_wq in kfd_interrupt_init()

hulk inclusion
category: bugfix
bugzilla: 13690
CVE: CVE-2019-16229

-------------------------------------------------

There are multiple points in the Linux Kernel where alloc_workqueue is
not getting checked for errors and as a result, a potential NULL
dereference could occur.
https://lkml.org/lkml/2019/9/9/487Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>
Reviewed-by: NWenan Mao <maowenan@huawei.com>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>

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

@@ -62,6 +62,11 @@ int kfd_interrupt_init(struct kfd_dev *kfd)
 	}
 
 	kfd->ih_wq = alloc_workqueue("KFD IH", WQ_HIGHPRI, 1);
+	if (!kfd->ih_wq) {
+		kfifo_free(&kfd->ih_fifo);
+		dev_err(kfd_chardev(), "Failed to allocate KFD IH workqueue\n");
+		return -ENOMEM;
+	}
 	spin_lock_init(&kfd->interrupt_lock);
 
 	INIT_WORK(&kfd->interrupt_work, interrupt_wq);