netdev - Re: [PATCH net-next v5] mctp: Implement extended addressing

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Message-ID: <f40cddba6f6fae5d3106da33a2968543d00d64e2.camel@codeconstruct.com.au>
Date:   Tue, 26 Oct 2021 09:55:08 +0800
From:   Jeremy Kerr <jk@...econstruct.com.au>
To:     David Miller <davem@...emloft.net>
Cc:     netdev@...r.kernel.org, kuba@...nel.org, matt@...econstruct.com.au,
        esyr@...hat.com
Subject: Re: [PATCH net-next v5] mctp: Implement extended addressing

Hi David,

> putting a variably sized type in the skb control blocxk is not a good
> idea.  Overruns will be silent, nothing in the typing protects you
> from udsing more space han exists in skb->cb.

There is a check using MCTP_SKB_CB_HADDR_MAXLEN, but setting the size of
the struct member typing would allow for better enforcement, yes.

> Plrease find another way, thank you.

OK, we can use MAX_ADDR_LEN here; we currently have enough space in the
cb for the maximum possible addressing sizes (and can check that through
a BUILD_BUG_ON too).

v6 coming right up.

Cheers,

Jeremy