From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Dumazet Subject: Re: [PATCH v2] cgroup: fix panic in netprio_cgroup Date: Sun, 08 Jul 2012 21:50:43 +0200 Message-ID: <1341777043.3265.1786.camel@edumazet-glaptop> References: <1341480520-25081-1-git-send-email-gaofeng@cn.fujitsu.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: davem@davemloft.net, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, tj@kernel.org, lizefan@huawei.com To: Gao feng , nhorman@tuxdriver.com Return-path: In-Reply-To: <1341480520-25081-1-git-send-email-gaofeng@cn.fujitsu.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org 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 > --- > 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 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();