Re: [PATCH] rtnetlink: fix data overflow in rtnl_calcit()

[Jakub Kicinski <kuba@kernel.org>]

On Mon, 19 Oct 2020 01:59:19 +0000 zhudi (J) wrote:
> > zhudi, why not use size_t? Seems like the most natural fit for counting size.  
> 
> Thanks for your replying.
> min_dump_alloc original type used is u16 and it's eventually assigned to 
> struct netlink_callback{}. min_dump_alloc which data type is u32. So I just simply
> promote to u32.
> Should be used size_t instead of u32?

I had a closer look, and I agree that u32 should be fine in struct
netlink_dump_control, rtnetlink_rcv_msg(), and as a return value from
rtnl_calcit().

But please use size_t for the local variable in rtnl_calcit().
This way you can convert the max_t() to a max().

When you send v2 please move the declaration of min_ifinfo_dump_size
after struct net *net = sock_net(skb->sk); (to get closer to longest 
to shortest declaration order).