[PATCH net] macvlan: fix null pointer dereference in macvlan_changelink_sources()

[wangyunjian]

From: Yunjian Wang <wangyunj...@huawei.com>

Currently pointer data is dereferenced when declaring addr before
pointer data is null checked. This could lead to a null pointer
dereference. Fix this by checking if pointer data is null first.

Fixes: 79cf79abce71 ("macvlan: add source mode")
Signed-off-by: Yunjian Wang <wangyunj...@huawei.com>
---
 drivers/net/macvlan.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/macvlan.c b/drivers/net/macvlan.c
index fb51329f8964..e412fd6b6798 100644
--- a/drivers/net/macvlan.c
+++ b/drivers/net/macvlan.c
@@ -1356,7 +1356,7 @@ static int macvlan_changelink_sources(struct macvlan_dev 
*vlan, u32 mode,
        struct nlattr *nla, *head;
        struct macvlan_source_entry *entry;
 
-       if (data[IFLA_MACVLAN_MACADDR])
+       if (data && data[IFLA_MACVLAN_MACADDR])
                addr = nla_data(data[IFLA_MACVLAN_MACADDR]);
 
        if (mode == MACVLAN_MACADDR_ADD) {
-- 
2.23.0