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Subject: Re: [PATCH] new UDPCP Communication Protocol
From: Eric Dumazet <eric.dumazet@gmail.com>
To: stefani@seibold.net
Cc: linux-kernel@vger.kernel.org, akpm@linux-foundation.org,
        davem@davemloft.net, netdev@vger.kernel.org, shemminger@vyatta.com,
        jj@chaosbits.net, daniel.baluta@gmail.com, jochen@jochen.org
In-Reply-To: <1294007971-18878-1-git-send-email-stefani@seibold.net>
References: <1294007971-18878-1-git-send-email-stefani@seibold.net>
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Date: Sun, 02 Jan 2011 23:49:22 +0100
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Le dimanche 02 janvier 2011 à 23:39 +0100, stefani@seibold.net a écrit :
> +
> +/*
> + * Create a new destination descriptor for the given IPV4 address and port
> + */
> +static struct udpcp_dest *new_dest(struct sock *sk, __be32 addr, __be16 port)
> +{
> +	struct udpcp_dest *dest;
> +	struct udpcp_sock *usk = udpcp_sk(sk);
> +
> +	if (usk->connections >= udpcp_max_connections)
> +		return NULL;
> +
> +	dest = kzalloc(sizeof(*dest), sk->sk_allocation);
> +
> +	if (dest) {
> +		usk->connections++;
> +		skb_queue_head_init(&dest->xmit);
> +		dest->addr = addr;
> +		dest->port = port;
> +		dest->ackmode = UDPCP_ACK;
> +		list_add_tail(&dest->list, &usk->destlist);
> +	}
> +
> +	return dest;
> +}
> +

Hmm, so 'connections' is increased, never decreased.

This seems a fatal flaw in this protocol, since a malicious user can
easily fill the list with garbage, and block regular communications.