linux-kernel - Re: [PATCH] ip6_offload: check segs for NULL in ipv6_gso

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Message-ID: <1480602847.18162.288.camel@edumazet-glaptop3.roam.corp.google.com>
Date:   Thu, 01 Dec 2016 06:34:07 -0800
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     Artem Savkov <asavkov@...hat.com>
Cc:     davem@...emloft.net, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, jstancek@...hat.com,
        steffen.klassert@...unet.com, alexander.h.duyck@...el.com
Subject: Re: [PATCH] ip6_offload: check segs for NULL in ipv6_gso_segment.

On Thu, 2016-12-01 at 14:06 +0100, Artem Savkov wrote:
> segs needs to be checked for being NULL in ipv6_gso_segment() before calling
> skb_shinfo(segs), otherwise kernel can run into a NULL-pointer dereference:


> Signed-off-by: Artem Savkov <asavkov@...hat.com>
> ---
>  

> diff --git a/net/ipv6/ip6_offload.c b/net/ipv6/ip6_offload.c
> index 1fcf61f..89c59e6 100644
> --- a/net/ipv6/ip6_offload.c
> +++ b/net/ipv6/ip6_offload.c
> @@ -99,7 +99,7 @@ static struct sk_buff *ipv6_gso_segment(struct sk_buff *skb,
>  		segs = ops->callbacks.gso_segment(skb, features);
>  	}
>  
> -	if (IS_ERR(segs))
> +	if (IS_ERR_OR_NULL(segs))
>  		goto out;
>  
>  	gso_partial = !!(skb_shinfo(segs)->gso_type & SKB_GSO_PARTIAL);

Do you know when was this bug added ?

Are you sure this is the right fix ?

Which gso_segment() is returning NULL exactly ?

Thanks.