On Thu, 2012-07-05 at 17:28 +0800, Gao feng wrote:
> we set max_prioidx to the first zero bit index of prioidx_map in
> function get_prioidx.
>
> So when we delete the low index netprio cgroup and adding a new
> netprio cgroup again,the max_prioidx will be set to the low index.
>
> when we set the high index cgroup's net_prio.ifpriomap,the function
> write_priomap will call update_netdev_tables to alloc memory which
> size is sizeof(struct netprio_map) + sizeof(u32) * (max_prioidx + 1),
> so the size of array that map->priomap point to is max_prioidx +1,
> which is low than what we actually need.
>
> fix this by adding check in get_prioidx,only set max_prioidx when
> max_prioidx low than the new prioidx.
>
> Signed-off-by: Gao feng <gaof...@cn.fujitsu.com>
> ---
> net/core/netprio_cgroup.c | 3 ++-
> 1 files changed, 2 insertions(+), 1 deletions(-)
>
> diff --git a/net/core/netprio_cgroup.c b/net/core/netprio_cgroup.c
> index 5b8aa2f..aa907ed 100644
> --- a/net/core/netprio_cgroup.c
> +++ b/net/core/netprio_cgroup.c
> @@ -49,8 +49,9 @@ static int get_prioidx(u32 *prio)
> return -ENOSPC;
> }
> set_bit(prioidx, prioidx_map);
> + if (atomic_read(&max_prioidx) < prioidx)
> + atomic_set(&max_prioidx, prioidx);
> spin_unlock_irqrestore(&prioidx_map_lock, flags);
> - atomic_set(&max_prioidx, prioidx);
> *prio = prioidx;
> return 0;
> }
This patch seems fine to me.
Acked-by: Eric Dumazet <eduma...@google.com>
Neil, looking at this file, I believe something is wrong.
dev->priomap is allocated by extend_netdev_table() called from
update_netdev_tables(). And this is only called if write_priomap() is
called.
But if write_priomap() is not called, it seems we can have out of bounds
accesses in cgrp_destroy() and read_priomap()
What do you think of following patch ?
diff --git a/net/core/netprio_cgroup.c b/net/core/netprio_cgroup.c
index 5b8aa2f..80150d2 100644
--- a/net/core/netprio_cgroup.c
+++ b/net/core/netprio_cgroup.c
@@ -141,7 +141,7 @@ static void cgrp_destroy(struct cgroup *cgrp)
rtnl_lock();
for_each_netdev(&init_net, dev) {
map = rtnl_dereference(dev->priomap);
- if (map)
+ if (map && cs->prioidx < map->priomap_len)
map->priomap[cs->prioidx] = 0;
}
rtnl_unlock();
@@ -165,7 +165,7 @@ static int read_priomap(struct cgroup *cont, struct cftype
*cft,
rcu_read_lock();
for_each_netdev_rcu(&init_net, dev) {
map = rcu_dereference(dev->priomap);
- priority = map ? map->priomap[prioidx] : 0;
+ priority = (map && prioidx < map->priomap_len) ?
map->priomap[prioidx] : 0;
cb->fill(cb, dev->name, priority);
}
rcu_read_unlock();
--
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