[PATCH v2] ethtool: check the ethtool_ops is NULL in dev_ethtool

[Wang Weidong <wangweidong1@huawei.com>]

some drivers maybe not implement the ethtool_ops with only
set NULL to ethtool_ops. So when call the ethtool devx will
lead to a 'NULL pointer dereference'.

So add a check in dev_ethtool

Signed-off-by: Wang Weidong <wangweidong1@huawei.com>
---
Change note:

v2: fix a trailing whitespace/tab pointed out by Daniel

---
 net/core/ethtool.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/net/core/ethtool.c b/net/core/ethtool.c
index 30071de..c8cfd8f 100644
--- a/net/core/ethtool.c
+++ b/net/core/ethtool.c
@@ -1500,6 +1500,9 @@ int dev_ethtool(struct net *net, struct ifreq *ifr)
 			return -EPERM;
 	}
 
+	if (!dev->ethtool_ops)
+		return -EOPNOTSUPP;
+
 	if (dev->ethtool_ops->begin) {
 		rc = dev->ethtool_ops->begin(dev);
 		if (rc  < 0)
-- 
1.7.12