Re: [PATCH net] net: sctp: sctp_v6_get_dst: fix boolean test in dst cache

[Neil Horman <nhorman@tuxdriver.com>]

On Wed, Feb 13, 2013 at 12:30:16AM +0100, Daniel Borkmann wrote:
> We walk through the bind address list and try to get the best source
> address for a given destination. However, currently, we take the
> 'continue' path of the loop when an entry is invalid (!laddr->valid)
> *and* the entry state does not equal SCTP_ADDR_SRC (laddr->state !=
> SCTP_ADDR_SRC).
> 
> Thus, still, invalid entries with SCTP_ADDR_SRC might not 'continue'
> as well as valid entries with SCTP_ADDR_{NEW, SRC, DEL}, with a possible
> false baddr and matchlen as a result, causing in worst case dst route
> to be false or possibly NULL.
> 
> This test should actually be a '||' instead of '&&'. But lets fix it
> and make this a bit easier to read by having the condition the same way
> as similarly done in sctp_v4_get_dst.
> 
> Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
> ---
>  net/sctp/ipv6.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/net/sctp/ipv6.c b/net/sctp/ipv6.c
> index f3f0f4d..391a245 100644
> --- a/net/sctp/ipv6.c
> +++ b/net/sctp/ipv6.c
> @@ -326,9 +326,10 @@ static void sctp_v6_get_dst(struct sctp_transport *t, union sctp_addr *saddr,
>  	 */
>  	rcu_read_lock();
>  	list_for_each_entry_rcu(laddr, &bp->address_list, list) {
> -		if (!laddr->valid && laddr->state != SCTP_ADDR_SRC)
> +		if (!laddr->valid)
>  			continue;
> -		if ((laddr->a.sa.sa_family == AF_INET6) &&
> +		if ((laddr->state == SCTP_ADDR_SRC) &&
> +		    (laddr->a.sa.sa_family == AF_INET6) &&
>  		    (scope <= sctp_scope(&laddr->a))) {
>  			bmatchlen = sctp_v6_addr_match_len(daddr, &laddr->a);
>  			if (!baddr || (matchlen < bmatchlen)) {
> -- 
> 1.7.11.7
> 
> --
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Acked-by: Neil Horman <nhorman@tuxdriver.com>