[Patch net] rtnetlink: allocate more memory for dev_set_mac_address()

[Cong Wang]

virtnet_set_mac_address() interprets mac address as struct
sockaddr, but upper layer only allocates dev->addr_len
which is ETH_ALEN + sizeof(sa_family_t) in this case.

We lack a unified definition for mac address, so just fix
the upper layer, this also allows drivers to interpret it
to struct sockaddr freely.

Reported-by: David Ahern <dsah...@gmail.com>
Signed-off-by: Cong Wang <xiyou.wangc...@gmail.com>
---
 net/core/rtnetlink.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index d1ba90980be1..ebaa26cf777f 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -2031,7 +2031,8 @@ static int do_setlink(const struct sk_buff *skb,
                struct sockaddr *sa;
                int len;
 
-               len = sizeof(sa_family_t) + dev->addr_len;
+               len = sizeof(sa_family_t) + max_t(size_t, dev->addr_len,
+                                                 sizeof(*sa));
                sa = kmalloc(len, GFP_KERNEL);
                if (!sa) {
                        err = -ENOMEM;
-- 
2.13.0