From mboxrd@z Thu Jan  1 00:00:00 1970
From: David Ahern <dsahern@gmail.com>
Subject: Re: [patch net-next RFC 1/9] net_sch: red: Add offload ability to RED
 qdisc
Date: Tue, 31 Oct 2017 08:59:08 -0600
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Cc: Nogah Frankel <nogahf@mellanox.com>,
        David Miller <davem@davemloft.net>,
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To: Jiri Pirko <jiri@resnulli.us>
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On 10/31/17 1:41 AM, Jiri Pirko wrote:
>>
>> If it is read-only, then attempts to set it from userspace should cause
>> the command to fail.
> 
> That breaks uapi. Consider existing userspace app sending garbage in
> that bit and new kernel which randomly fails upon the garbage.
> 

It is called syzkaller. The kernel should always validate userspace
config including checking that unused bits are 0. So you are saying tc
has never done that checking and just ignored bits that are not valid?