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: Di Zhu <zhudi21@huawei.com>
Link: https://lore.kernel.org/r/20201021020053.1401-1-zhudi21@huawei.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/include/linux/netlink.h b/include/linux/netlink.h
index 666cd03..9f11877 100644 (file)
--- a/include/linux/netlink.h
+++ b/include/linux/netlink.h
@@ -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,

diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index 68e0682..7d72236 100644 (file)
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -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) {