netdev - Re: [PATCH net] net: netlink: Fix uninit-value in netlink

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Date:   Fri, 6 Dec 2019 10:47:54 -0800
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     Håkon Bugge <haakon.bugge@...cle.com>,
        "David S . Miller" <davem@...emloft.net>
Cc:     netdev@...r.kernel.org
Subject: Re: [PATCH net] net: netlink: Fix uninit-value in netlink_recvmsg()



On 12/6/19 5:49 AM, Håkon Bugge wrote:
> If skb_recv_datagram() returns NULL, netlink_recvmsg() will return an
> arbitrarily value.
> 
> Signed-off-by: Håkon Bugge <haakon.bugge@...cle.com>
> ---
>  net/netlink/af_netlink.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
> index 90b2ab9dd449..bb7276f9c9f8 100644
> --- a/net/netlink/af_netlink.c
> +++ b/net/netlink/af_netlink.c
> @@ -1936,6 +1936,7 @@ static int netlink_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
>  		return -EOPNOTSUPP;
>  
>  	copied = 0;
> +	err = 0;
>  
>  	skb = skb_recv_datagram(sk, flags, noblock, &err);
>  	if (skb == NULL)
> 

Please provide a Fixes: tag

By doing the research, you probably would find there is no bug.

err is set in skb_recv_datagram() when there is no packet to read.