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



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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: Miaoqian Lin <linmq006@gmail.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20220602104223.54527-1-linmq006@gmail.com


Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Ovidiu Panait <ovidiu.panait@windriver.com>
Signed-off-by: Guo Mengqi <guomengqi3@huawei.com>
Reviewed-by: Xiu Jianfeng <xiujianfeng@huawei.com>
Reviewed-by: Weilong Chen <chenweilong@huawei.com>
Signed-off-by: Jialin Zhang <zhangjialin11@huawei.com>