[ovs-dev] [PATCH] ofproto: Fix bad memory access sending large numbers of port stats replies.

[Justin Pettit]

Looks good.

--Justin


On Apr 26, 2010, at 3:40 PM, Ben Pfaff wrote:

> The append_stats_reply() function can modify its pointer argument, but
> append_port_stat() was failing to propagate this change back to its own
> caller.  So when append_stats_reply() did in fact modify it (which happens
> when the 64 kB maximum OpenFlow message length was exceeded), the
> handle_port_stats_request() function would then access freed memory on the
> next call to append_port_stat().
> 
> Bug #2714.
> Reported-by: Ram Jothikumar <rjothikumar at nicira.com>
> Debugging help by Justin Pettit <jpettit at nicira.com>
> ---
> ofproto/ofproto.c |    8 ++++----
> 1 files changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/ofproto/ofproto.c b/ofproto/ofproto.c
> index 3f9cc90..6c93aea 100644
> --- a/ofproto/ofproto.c
> +++ b/ofproto/ofproto.c
> @@ -2760,7 +2760,7 @@ handle_table_stats_request(struct ofproto *p, struct ofconn *ofconn,
> 
> static void
> append_port_stat(struct ofport *port, uint16_t port_no, struct ofconn *ofconn, 
> -                 struct ofpbuf *msg)
> +                 struct ofpbuf **msgp)
> {
>     struct netdev_stats stats;
>     struct ofp_port_stats *ops;
> @@ -2770,7 +2770,7 @@ append_port_stat(struct ofport *port, uint16_t port_no, struct ofconn *ofconn,
>      * netdev_get_stats() will log errors. */
>     netdev_get_stats(port->netdev, &stats);
> 
> -    ops = append_stats_reply(sizeof *ops, ofconn, &msg);
> +    ops = append_stats_reply(sizeof *ops, ofconn, msgp);
>     ops->port_no = htons(odp_port_to_ofp_port(port_no));
>     memset(ops->pad, 0, sizeof ops->pad);
>     ops->rx_packets = htonll(stats.rx_packets);
> @@ -2808,11 +2808,11 @@ handle_port_stats_request(struct ofproto *p, struct ofconn *ofconn,
>         port = port_array_get(&p->ports, 
>                 ofp_port_to_odp_port(ntohs(psr->port_no)));
>         if (port) {
> -            append_port_stat(port, ntohs(psr->port_no), ofconn, msg);
> +            append_port_stat(port, ntohs(psr->port_no), ofconn, &msg);
>         }
>     } else {
>         PORT_ARRAY_FOR_EACH (port, &p->ports, port_no) {
> -            append_port_stat(port, port_no, ofconn, msg);
> +            append_port_stat(port, port_no, ofconn, &msg);
>         }
>     }
> 
> -- 
> 1.6.6.1
> 
> 
> _______________________________________________
> dev mailing list
> dev at openvswitch.org
> http://openvswitch.org/mailman/listinfo/dev_openvswitch.org