netdev - Re: [PATCH] netlink: fix null pointer dereference on nlk->groups

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Date:	Fri, 8 Jan 2016 22:43:22 +0300
From:	Sergei Shtylyov <sergei.shtylyov@...entembedded.com>
To:	Baozeng Ding <sploving1@...il.com>, davem@...emloft.net,
	herbert@...dor.apana.org.au, daniel@...earbox.net, tgraf@...g.ch,
	pablo@...filter.org, chamaken@...il.com, nicolas.dichtel@...nd.com,
	fw@...len.de
Cc:	netdev@...r.kernel.org
Subject: Re: [PATCH] netlink: fix null pointer dereference on nlk->groups

Hello.

On 01/08/2016 08:46 AM, Baozeng Ding wrote:

> If groups is not 0 and nlk->groups is NULL, it will not return
> immediately and cause a null pointer dereference later.
>
> Signed-off-by: Baozeng Ding <sploving1@...il.com>
> ---
>   net/netlink/af_netlink.c | 10 +++++++---
>   1 file changed, 7 insertions(+), 3 deletions(-)
>
> diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
> index 59651af..38efde0 100644
> --- a/net/netlink/af_netlink.c
> +++ b/net/netlink/af_netlink.c
[...]
> @@ -1576,14 +1577,17 @@ static int netlink_bind(struct socket *sock, struct sockaddr *addr,
>   		}
>   	}
>
> -	if (!groups && (nlk->groups == NULL || !(u32)nlk->groups[0]))
> +	if (nlk->groups == NULL)

    '!nlk->groups' is preferred in the networking code.

[...]

MBR, Sergei