drm/virtio: Fix NULL vs IS_ERR checking in virtio_gpu_object_shmem_init

stable inclusion
from stable-v5.10.171
commit 0a4181b23acf53e9c95b351df6a7891116b98f9b
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/I6IKWF
CVE: CVE-2023-22998

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=0a4181b23acf53e9c95b351df6a7891116b98f9b

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

commit c2496873 upstream.

Since drm_prime_pages_to_sg() function return error pointers.
The drm_gem_shmem_get_sg_table() function returns error pointers too.
Using IS_ERR() to check the return value to fix this.

Fixes: 2f2aa137 ("drm/virtio: move virtio_gpu_mem_entry initialization to new function")
Signed-off-by: NMiaoqian Lin <linmq006@gmail.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20220602104223.54527-1-linmq006@gmail.comSigned-off-by: NGerd Hoffmann <kraxel@redhat.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NOvidiu Panait <ovidiu.panait@windriver.com>
Signed-off-by: NGuo Mengqi <guomengqi3@huawei.com>
Reviewed-by: NXiu Jianfeng <xiujianfeng@huawei.com>
Reviewed-by: NWeilong Chen <chenweilong@huawei.com>
Signed-off-by: NJialin Zhang <zhangjialin11@huawei.com>

drivers/gpu/drm/virtio/virtgpu_object.c

@@ -157,9 +157,9 @@ static int virtio_gpu_object_shmem_init(struct virtio_gpu_device *vgdev,
 	 * since virtio_gpu doesn't support dma-buf import from other devices.
 	 */
 	shmem->pages = drm_gem_shmem_get_sg_table(&bo->base.base);
-	if (!shmem->pages) {
+	if (IS_ERR(shmem->pages)) {
 		drm_gem_shmem_unpin(&bo->base.base);
-		return -EINVAL;
+		return PTR_ERR(shmem->pages);
 	}
 
 	if (use_dma_api) {