netdev - Re: [v2] Fix NULL dereference in x25

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Date:	Wed, 02 Nov 2011 03:30:17 +0100
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Dave Jones <davej@...hat.com>
Cc:	netdev@...r.kernel.org, Matthew Daley <mattjd@...il.com>
Subject: Re: [v2] Fix NULL dereference in x25_recvmsg

Le mardi 01 novembre 2011 à 22:26 -0400, Dave Jones a écrit :
> commit cb101ed2 in 3.0 introduced a bug in x25_recvmsg()
> When passed bogus junk from userspace, x25->neighbour can be NULL,
> as shown in this oops..
> 
...
> Signed-off-by: Dave Jones <davej@...hat.com>
> 
> diff --git a/net/x25/af_x25.c b/net/x25/af_x25.c
> index 5f03e4e..3e16c6a 100644
> --- a/net/x25/af_x25.c
> +++ b/net/x25/af_x25.c
> @@ -1261,14 +1261,19 @@ static int x25_recvmsg(struct kiocb *iocb, struct socket *sock,
>  	struct x25_sock *x25 = x25_sk(sk);
>  	struct sockaddr_x25 *sx25 = (struct sockaddr_x25 *)msg->msg_name;
>  	size_t copied;
> -	int qbit, header_len = x25->neighbour->extended ?
> -		X25_EXT_MIN_LEN : X25_STD_MIN_LEN;
> -
> +	int qbit, header_len;
>  	struct sk_buff *skb;
>  	unsigned char *asmptr;
>  	int rc = -ENOTCONN;
>  
>  	lock_sock(sk);
> +
> +	if (x25->neighbour == NULL)
> +		goto out;
> +
> +	header_len = x25->neighbour->extended ?
> +		X25_EXT_MIN_LEN : X25_STD_MIN_LEN;
> +
>  	/*
>  	 * This works for seqpacket too. The receiver has ordered the queue for
>  	 * us! We do one quick check first though

Acked-by: Eric Dumazet <eric.dumazet@...il.com>


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