netdev - Re: [PATCH iproute2] iplink: work around rtattr length limits for IFLA_VFINFO

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Date:   Mon, 18 Jan 2021 10:36:57 -0700
From:   David Ahern <dsahern@...il.com>
To:     Edwin Peer <edwin.peer@...adcom.com>
Cc:     Jakub Kicinski <kuba@...nel.org>,
        Michal Kubecek <mkubecek@...e.cz>,
        netdev <netdev@...r.kernel.org>,
        Stephen Hemminger <stephen@...workplumber.org>,
        Andrew Gospodarek <andrew.gospodarek@...adcom.com>,
        Michael Chan <michael.chan@...adcom.com>
Subject: Re: [PATCH iproute2] iplink: work around rtattr length limits for
 IFLA_VFINFO_LIST

On 1/18/21 10:34 AM, Edwin Peer wrote:
> On Sun, Jan 17, 2021 at 7:48 PM David Ahern <dsahern@...il.com> wrote:
> 
>> IMHO this is a kernel bug that should be fixed. An easy fix to check the
>> overflow in nla_nest_end and return an error. Sadly, nla_nest_end return
>> code is ignored and backporting any change to fix that will be
>> nightmare. A warning will identify places that need to be fixed.
> 
> Assuming we fix nla_nest_end() and error in some way, how does that
> assist iproute2?
> 

I don't follow. The kernel is sending a malformed message; userspace
should not be guessing at how to interpret it.