Re: [PATCH 2.6 NET] Fixes slab corruption in cbq_destroy

[Patrick McHardy <kaber@xxxxxxxxx>]

Thomas Graf wrote:

> Fixes slab corruption in cbq_destroy. cbq_destroy_filters and
> qdisc_put_rtab(q->link.R_tab) are already called in cbq_destroy_class.
> The latter lead to a slab corruption due to repeated freeing of
> q->link.R_tab because q->link is part of q->classes. Problem introduced
> in 1.21.
>  
I don't see how there can be slab corruption. qdisc_put_rtab only
calls kfree if the table is found in qdisc_rtab_list, which only
happens once. But the patch is still fine as cleanup :)

Regards
Patrick

> Signed-off-by: Thomas Graf <tgraf@xxxxxxx>
>
>
> --- linux-2.6.9-rc2-bk2.orig/net/sched/sch_cbq.c    2004-09-16 
> 14:52:23.000000000 +0200
> +++ linux-2.6.9-rc2-bk2/net/sched/sch_cbq.c     2004-09-16 14:53:53.000000000 
> +0200
> @@ -1770,10 +1770,6 @@
> #ifdef CONFIG_NET_CLS_POLICE
>         q->rx_class = NULL;
> #endif
> -       for (h = 0; h < 16; h++) {
> -               for (cl = q->classes[h]; cl; cl = cl->next)
> -                       cbq_destroy_filters(cl);
> -       }
>
>         for (h = 0; h < 16; h++) {
>                 struct cbq_class *next;
> @@ -1783,8 +1779,6 @@
>                         cbq_destroy_class(sch, cl);
>                 }
>         }
> -
> -       qdisc_put_rtab(q->link.R_tab);
> }
>
> static void cbq_put(struct Qdisc *sch, unsigned long arg)
>
>