linux-kernel - Re: [PATCH] net: geneve: modify IP header check in geneve6_xmit

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Message-ID: <20210422003942.GF4841@breakpoint.cc>
Date:   Thu, 22 Apr 2021 02:39:42 +0200
From:   Florian Westphal <fw@...len.de>
To:     Phillip Potter <phil@...lpotter.co.uk>
Cc:     davem@...emloft.net, kuba@...nel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, edumazet@...gle.com
Subject: Re: [PATCH] net: geneve: modify IP header check in geneve6_xmit_skb

Phillip Potter <phil@...lpotter.co.uk> wrote:
> Modify the check in geneve6_xmit_skb to use the size of a struct iphdr
> rather than struct ipv6hdr. This fixes two kernel selftest failures
> introduced by commit 6628ddfec758
> ("net: geneve: check skb is large enough for IPv4/IPv6 header"), without
> diminishing the fix provided by that commit.

What errors?

> Reported-by: kernel test robot <oliver.sang@...el.com>
> Signed-off-by: Phillip Potter <phil@...lpotter.co.uk>
> ---
>  drivers/net/geneve.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/net/geneve.c b/drivers/net/geneve.c
> index 42f31c681846..a57a5e6f614f 100644
> --- a/drivers/net/geneve.c
> +++ b/drivers/net/geneve.c
> @@ -988,7 +988,7 @@ static int geneve6_xmit_skb(struct sk_buff *skb, struct net_device *dev,
>  	__be16 sport;
>  	int err;
>  
> -	if (!pskb_network_may_pull(skb, sizeof(struct ipv6hdr)))
> +	if (!pskb_network_may_pull(skb, sizeof(struct iphdr)))
>  		return -EINVAL;

Seems this is papering over some bug, this change makes no sense to
me.  Can you please explain this?