netdev - Re: [PATCH net] ipv6: make sure dev is not NULL before call ip6_frag

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Message-ID: <1494255030.7796.56.camel@edumazet-glaptop3.roam.corp.google.com>
Date:   Mon, 08 May 2017 07:50:30 -0700
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     Hangbin Liu <liuhangbin@...il.com>
Cc:     netdev@...r.kernel.org
Subject: Re: [PATCH net] ipv6: make sure dev is not NULL before call
 ip6_frag_reasm

On Mon, 2017-05-08 at 11:09 +0800, Hangbin Liu wrote:
> Since ip6_frag_reasm() will call __in6_dev_get(dev), which will access
> dev->ip6_ptr. We need to make sure dev is not NULL.
> 
> Signed-off-by: Hangbin Liu <liuhangbin@...il.com>
> ---
>  net/ipv6/reassembly.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/net/ipv6/reassembly.c b/net/ipv6/reassembly.c
> index e1da5b8..e3ebd62 100644
> --- a/net/ipv6/reassembly.c
> +++ b/net/ipv6/reassembly.c
> @@ -348,7 +348,7 @@ static int ip6_frag_queue(struct frag_queue *fq, struct sk_buff *skb,
>  		fq->q.flags |= INET_FRAG_FIRST_IN;
>  	}
>  
> -	if (fq->q.flags == (INET_FRAG_FIRST_IN | INET_FRAG_LAST_IN) &&
> +	if (dev && fq->q.flags == (INET_FRAG_FIRST_IN | INET_FRAG_LAST_IN) &&
>  	    fq->q.meat == fq->q.len) {
>  		int res;
>  		unsigned long orefdst = skb->_skb_refdst;


How dev could be possibly NULL here ?