netdev - Re: [PATCH net] macsec: avoid to set wrong mtu

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Message-Id: <20200424.164327.455293620342341833.davem@davemloft.net>
Date:   Fri, 24 Apr 2020 16:43:27 -0700 (PDT)
From:   David Miller <davem@...emloft.net>
To:     ap420073@...il.com
Cc:     kuba@...nel.org, sd@...asysnail.net, netdev@...r.kernel.org
Subject: Re: [PATCH net] macsec: avoid to set wrong mtu

From: Taehee Yoo <ap420073@...il.com>
Date: Thu, 23 Apr 2020 13:40:47 +0000

> When a macsec interface is created, the mtu is calculated with the lower
> interface's mtu value.
> If the mtu of lower interface is lower than the length, which is needed
> by macsec interface, macsec's mtu value will be overflowed.
> So, if the lower interface's mtu is too low, macsec interface's mtu
> should be set to 0.
> 
> Test commands:
>     ip link add dummy0 mtu 10 type dummy
>     ip link add macsec0 link dummy0 type macsec
>     ip link show macsec0
> 
> Before:
>     11: macsec0@...my0: <BROADCAST,MULTICAST,M-DOWN> mtu 4294967274
> After:
>     11: macsec0@...my0: <BROADCAST,MULTICAST,M-DOWN> mtu 0
> 
> Fixes: c09440f7dcb3 ("macsec: introduce IEEE 802.1AE driver")
> Signed-off-by: Taehee Yoo <ap420073@...il.com>

Applied and queued up for -stable.