linux-kernel - Re: [PATCH v2 net] ipv6: Fix dangling pointer when ipv6 fragment

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Message-ID: <20190401163355.4fokjjbyv3ug7nl3@kafai-mbp.dhcp.thefacebook.com>
Date:   Mon, 1 Apr 2019 16:34:01 +0000
From:   Martin Lau <kafai@...com>
To:     hujunwei <hujunwei4@...wei.com>
CC:     "davem@...emloft.net" <davem@...emloft.net>,
        "kuznet@....inr.ac.ru" <kuznet@....inr.ac.ru>,
        "yoshfuji@...ux-ipv6.org" <yoshfuji@...ux-ipv6.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "mingfangsen@...wei.com" <mingfangsen@...wei.com>,
        "liuzhiqiang26@...wei.com" <liuzhiqiang26@...wei.com>,
        "zhangwenhao8@...wei.com" <zhangwenhao8@...wei.com>,
        "wangxiaogang3@...wei.com" <wangxiaogang3@...wei.com>
Subject: Re: [PATCH v2 net] ipv6: Fix dangling pointer when ipv6 fragment

On Sun, Mar 31, 2019 at 05:04:29PM +0800, hujunwei wrote:
> From: Junwei Hu <hujunwei4@...wei.com>
> 
> At the beginning of ip6_fragment func, the prevhdr pointer is
> obtained in the ip6_find_1stfragopt func.
> However, all the pointers pointing into skb header may change
> when calling skb_checksum_help func with
> skb->ip_summed = CHECKSUM_PARTIAL condition.
> The prevhdr pointe will be dangling if it is not reloaded after
> calling __skb_linearize func in skb_checksum_help func.
> 
> Here, I add a variable, nexthdr_offset, to evaluate the offset,
> which does not changes even after calling __skb_linearize func.
Acked-by: Martin KaFai Lau <kafai@...com>