netdevice: add the case if dev is NULL

stable inclusion
from stable-v4.19.238
commit 574a12b4445076a04499962ce8b8ae15f75a7955
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/I51YBN
CVE: CVE-2022-28356

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

commit b37a4668 upstream.

Add the case if dev is NULL in dev_{put, hold}, so the caller doesn't
need to care whether dev is NULL or not.
Signed-off-by: NYajun Deng <yajun.deng@linux.dev>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
Cc: Pavel Machek <pavel@denx.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NHuang Guobin <huangguobin4@huawei.com>
Reviewed-by: NWei Yongjun <weiyongjun1@huawei.com>
Reviewed-by: NXiu Jianfeng <xiujianfeng@huawei.com>
Signed-off-by: NYongqiang Liu <liuyongqiang13@huawei.com>

include/linux/netdevice.h

@@ -3790,7 +3790,8 @@ void netdev_run_todo(void);
  */
 static inline void dev_put(struct net_device *dev)
 {
-	this_cpu_dec(*dev->pcpu_refcnt);
+	if (dev)
+		this_cpu_dec(*dev->pcpu_refcnt);
 }
 
 /**
@@ -3801,7 +3802,8 @@ static inline void dev_put(struct net_device *dev)
  */
 static inline void dev_hold(struct net_device *dev)
 {
-	this_cpu_inc(*dev->pcpu_refcnt);
+	if (dev)
+		this_cpu_inc(*dev->pcpu_refcnt);
 }
 
 /* Carrier loss detection, dial on demand. The functions netif_carrier_on