Commit a2939745 authored by Jakub Kicinski's avatar Jakub Kicinski Committed by David S. Miller
Browse files

rtnetlink: avoid frame size warning in rtnl_newlink() 



Standard kernel compilation produces the following warning:

net/core/rtnetlink.c: In function ‘rtnl_newlink’:
net/core/rtnetlink.c:3232:1: warning: the frame size of 1288 bytes is larger than 1024 bytes [-Wframe-larger-than=]
 }
  ^

This should not really be an issue, as rtnl_newlink() stack is
generally quite shallow.

Fix the warning by allocating attributes with kmalloc() in a wrapper
and passing it down to rtnl_newlink(), avoiding complexities on error
paths.

Alternatively we could kmalloc() some structure within rtnl_newlink(),
slave attributes look like a good candidate.  In practice it adds to
already rather high complexity and length of the function.

Signed-off-by: default avatarJakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: default avatarDavid Ahern <dsahern@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 420d0318

net/core/rtnetlink.c

+17 −3
Original line number Diff line number Diff line
@@ -2971,14 +2971,13 @@ static int rtnl_group_changelink(const struct sk_buff *skb, 
	return 0;

}



static int rtnl_newlink(struct sk_buff *skb, struct nlmsghdr *nlh,

			struct netlink_ext_ack *extack)

static int __rtnl_newlink(struct sk_buff *skb, struct nlmsghdr *nlh,

			  struct nlattr **attr, struct netlink_ext_ack *extack)

{

	struct nlattr *slave_attr[RTNL_SLAVE_MAX_TYPE + 1];

	unsigned char name_assign_type = NET_NAME_USER;

	struct nlattr *linkinfo[IFLA_INFO_MAX + 1];

	const struct rtnl_link_ops *m_ops = NULL;

	struct nlattr *attr[RTNL_MAX_TYPE + 1];

	struct net_device *master_dev = NULL;

	struct net *net = sock_net(skb->sk);

	const struct rtnl_link_ops *ops;
@@ -3226,6 +3225,21 @@ static int rtnl_newlink(struct sk_buff *skb, struct nlmsghdr *nlh, 
	goto out;

}



static int rtnl_newlink(struct sk_buff *skb, struct nlmsghdr *nlh,

			struct netlink_ext_ack *extack)

{

	struct nlattr **attr;

	int ret;



	attr = kmalloc_array(RTNL_MAX_TYPE + 1, sizeof(*attr), GFP_KERNEL);

	if (!attr)

		return -ENOMEM;



	ret = __rtnl_newlink(skb, nlh, attr, extack);

	kfree(attr);

	return ret;

}



static int rtnl_getlink(struct sk_buff *skb, struct nlmsghdr *nlh,

			struct netlink_ext_ack *extack)

{