vhost_vdpa: switch to vmemdup_user()

mainline inclusion
from mainline-v5.11-rc1
commit 0ab4b890
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I5WXCZ
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=0ab4b8901a8edda4fd1c2aded36192566d89353f

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

Replace opencoded alloc and copy with vmemdup_user()
Signed-off-by: NTian Tao <tiantao6@hisilicon.com>
Link: https://lore.kernel.org/r/1605057288-60400-1-git-send-email-tiantao6@hisilicon.comSigned-off-by: NMichael S. Tsirkin <mst@redhat.com>
Reviewed-by: NStefano Garzarella <sgarzare@redhat.com>
Signed-off-by: NPengyuan Zhao <zhaopengyuan@hisilicon.com>

drivers/vhost/vdpa.c

@@ -248,14 +248,10 @@ static long vhost_vdpa_set_config(struct vhost_vdpa *v,
 		return -EFAULT;
 	if (vhost_vdpa_config_validate(v, &config))
 		return -EINVAL;
-	buf = kvzalloc(config.len, GFP_KERNEL);
-	if (!buf)
-		return -ENOMEM;
 
-	if (copy_from_user(buf, c->buf, config.len)) {
-		kvfree(buf);
-		return -EFAULT;
-	}
+	buf = vmemdup_user(c->buf, config.len);
+	if (IS_ERR(buf))
+		return PTR_ERR(buf);
 
 	ops->set_config(vdpa, config.off, buf, config.len);