Commit ebfe3c51 authored by Di Zhu's avatar Di Zhu Committed by Jakub Kicinski
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rtnetlink: fix data overflow in rtnl_calcit() 



"ip addr show" command execute error when we have a physical
network card with a large number of VFs

The return value of if_nlmsg_size() in rtnl_calcit() will exceed
range of u16 data type when any network cards has a larger number of
VFs. rtnl_vfinfo_size() will significant increase needed dump size when
the value of num_vfs is larger.

Eventually we get a wrong value of min_ifinfo_dump_size because of overflow
which decides the memory size needed by netlink dump and netlink_dump()
will return -EMSGSIZE because of not enough memory was allocated.

So fix it by promoting  min_dump_alloc data type to u32 to
avoid whole netlink message size overflow and it's also align
with the data type of struct netlink_callback{}.min_dump_alloc
which is assigned by return value of rtnl_calcit()

Signed-off-by: default avatarDi Zhu <zhudi21@huawei.com>
Link: https://lore.kernel.org/r/20201021020053.1401-1-zhudi21@huawei.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent 5403caf2

include/linux/netlink.h

+1 −1
Original line number Diff line number Diff line
@@ -240,7 +240,7 @@ struct netlink_dump_control { 
	int (*done)(struct netlink_callback *);

	void *data;

	struct module *module;

	u16 min_dump_alloc;

	u32 min_dump_alloc;

};



int __netlink_dump_start(struct sock *ssk, struct sk_buff *skb,

net/core/rtnetlink.c

+6 −7
Original line number Diff line number Diff line
@@ -3709,13 +3709,13 @@ static int rtnl_dellinkprop(struct sk_buff *skb, struct nlmsghdr *nlh, 
	return rtnl_linkprop(RTM_DELLINKPROP, skb, nlh, extack);

}



static u16 rtnl_calcit(struct sk_buff *skb, struct nlmsghdr *nlh)

static u32 rtnl_calcit(struct sk_buff *skb, struct nlmsghdr *nlh)

{

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

	struct net_device *dev;

	size_t min_ifinfo_dump_size = 0;

	struct nlattr *tb[IFLA_MAX+1];

	u32 ext_filter_mask = 0;

	u16 min_ifinfo_dump_size = 0;

	struct net_device *dev;

	int hdrlen;



	/* Same kernel<->userspace interface hack as in rtnl_dump_ifinfo. */
@@ -3735,9 +3735,8 @@ static u16 rtnl_calcit(struct sk_buff *skb, struct nlmsghdr *nlh) 
	 */

	rcu_read_lock();

	for_each_netdev_rcu(net, dev) {

		min_ifinfo_dump_size = max_t(u16, min_ifinfo_dump_size,

					     if_nlmsg_size(dev,

						           ext_filter_mask));

		min_ifinfo_dump_size = max(min_ifinfo_dump_size,

					   if_nlmsg_size(dev, ext_filter_mask));

	}

	rcu_read_unlock();
@@ -5494,7 +5493,7 @@ static int rtnetlink_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh, 
	if (kind == 2 && nlh->nlmsg_flags&NLM_F_DUMP) {

		struct sock *rtnl;

		rtnl_dumpit_func dumpit;

		u16 min_dump_alloc = 0;

		u32 min_dump_alloc = 0;



		link = rtnl_get_link(family, type);

		if (!link || !link->dumpit) {