Re: [PATCH v2] cgroup: fix panic in netprio_cgroup
From: Eric Dumazet <hidden>
Date: 2012-07-08 19:50:49
Also in:
lkml
Subsystem:
networking [general], the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
On Thu, 2012-07-05 at 17:28 +0800, Gao feng wrote:
quoted hunk ↗ jump to hunk
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 <redacted> --- 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 <edumazet@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();