linux-kernel - Re: [PATCH 1/2] net: ipv4: Fix a possible null-pointer dereference in inet_csk_rebuild

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Date:   Sat, 27 Jul 2019 13:25:10 -0700 (PDT)
From:   David Miller <davem@...emloft.net>
To:     baijiaju1990@...il.com
Cc:     kuznet@....inr.ac.ru, yoshfuji@...ux-ipv6.org,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] net: ipv4: Fix a possible null-pointer dereference
 in inet_csk_rebuild_route()

From: Jia-Ju Bai <baijiaju1990@...il.com>
Date: Fri, 26 Jul 2019 10:25:34 +0800

> diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c
> index f5c163d4771b..27d9d80f3401 100644
> --- a/net/ipv4/inet_connection_sock.c
> +++ b/net/ipv4/inet_connection_sock.c
> @@ -1073,7 +1073,10 @@ static struct dst_entry *inet_csk_rebuild_route(struct sock *sk, struct flowi *f
>  		sk_setup_caps(sk, &rt->dst);
>  	rcu_read_unlock();
>  
> -	return &rt->dst;
> +	if (rt)
> +		return &rt->dst;
> +	else
> +		return NULL;

If rt is NULL, &rt->dst is also NULL as has been pointed out to you.

Please fix your automated tools to understand this case before submitting
more changes.

Thank you.