vdpa: Fix error logic in vdpa_nl_cmd_dev_get_doit

mainline inclusion
from mainline-v5.19-rc1
commit 7a6691f1
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=7a6691f1f89784f775fa0c54be57533445726068

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

In vdpa_nl_cmd_dev_get_doit(), if the call to genlmsg_reply() fails we
must not call nlmsg_free() since this is done inside genlmsg_reply().

Fix it.

Fixes: bc0d90ee ("vdpa: Enable user to query vdpa device info")
Reviewed-by: NSi-Wei Liu <si-wei.liu@oracle.com>
Acked-by: NJason Wang <jasowang@redhat.com>
Signed-off-by: NEli Cohen <elic@nvidia.com>
Message-Id: <20220518133804.1075129-2-elic@nvidia.com>
Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: NPengyuan Zhao <zhaopengyuan@hisilicon.com>

drivers/vdpa/vdpa.c

@@ -759,14 +759,19 @@ static int vdpa_nl_cmd_dev_get_doit(struct sk_buff *skb, struct genl_info *info)
 		goto mdev_err;
 	}
 	err = vdpa_dev_fill(vdev, msg, info->snd_portid, info->snd_seq, 0, info->extack);
-	if (!err)
-		err = genlmsg_reply(msg, info);
+	if (err)
+		goto mdev_err;
+
+	err = genlmsg_reply(msg, info);
+	put_device(dev);
+	mutex_unlock(&vdpa_dev_mutex);
+	return err;
+
 mdev_err:
 	put_device(dev);
 err:
 	mutex_unlock(&vdpa_dev_mutex);
-	if (err)
-		nlmsg_free(msg);
+	nlmsg_free(msg);
 	return err;
 }