Subject: Re: [PATCH net v4] sctp: asconf's process should verify address parameter is in the beginning

From: Vlad Yasevich <[email-masked]>
Date: Thu, 27 Aug 2015 08:46:15 -0400

On 08/27/2015 04:26 AM, Xin Long wrote:
> in sctp_process_asconf(), we get address parameter from the beginning of
> the addip params. but we never check if it's really there. if the addr
> param is not there, it still can pass sctp_verify_asconf(), then to be
> handled by sctp_process_asconf(), it will not be safe.
> 
> so add a code in sctp_verify_asconf() to check the address parameter is in
> the beginning, or return false to send abort.
> 
> note that this can also detect multiple address parameters, and reject it.
> 
> Signed-off-by: Xin Long <[email-masked]>
> Signed-off-by: Marcelo Ricardo Leitner <[email-masked]>

Looks good to me.

Acked-by: Vlad Yasevich <[email-masked]>

-vlad

> ---
>  net/sctp/sm_make_chunk.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/net/sctp/sm_make_chunk.c b/net/sctp/sm_make_chunk.c
> index 06320c8..a655ddc 100644
> --- a/net/sctp/sm_make_chunk.c
> +++ b/net/sctp/sm_make_chunk.c
> @@ -3132,11 +3132,18 @@ bool sctp_verify_asconf(const struct sctp_association *asoc,
>  		case SCTP_PARAM_IPV4_ADDRESS:
>  			if (length != sizeof(sctp_ipv4addr_param_t))
>  				return false;
> +			/* ensure there is only one addr param and it's in the
> +			 * beginning of addip_hdr params, or we reject it.
> +			 */
> +			if (param.v != addip->addip_hdr.params)
> +				return false;
>  			addr_param_seen = true;
>  			break;
>  		case SCTP_PARAM_IPV6_ADDRESS:
>  			if (length != sizeof(sctp_ipv6addr_param_t))
>  				return false;
> +			if (param.v != addip->addip_hdr.params)
> +				return false;
>  			addr_param_seen = true;
>  			break;
>  		case SCTP_PARAM_ADD_IP:
>