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Subject[PATCH] net: cgroup: fix out of bounds accesses
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Date
From: Eric Dumazet <edumazet@google.com>

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(), read_priomap() & skb_update_prio()

With help from Gao Feng

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Neil Horman <nhorman@tuxdriver.com>
Cc: Gao feng <gaofeng@cn.fujitsu.com>
---
net/core/dev.c | 8 ++++++--
net/core/netprio_cgroup.c | 4 ++--
2 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/net/core/dev.c b/net/core/dev.c
index 84f01ba..0f28a9e 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -2444,8 +2444,12 @@ static void skb_update_prio(struct sk_buff *skb)
{
struct netprio_map *map = rcu_dereference_bh(skb->dev->priomap);

- if ((!skb->priority) && (skb->sk) && map)
- skb->priority = map->priomap[skb->sk->sk_cgrp_prioidx];
+ if (!skb->priority && skb->sk && map) {
+ unsigned int prioidx = skb->sk->sk_cgrp_prioidx;
+
+ if (prioidx < map->priomap_len)
+ skb->priority = map->priomap[prioidx];
+ }
}
#else
#define skb_update_prio(skb)
diff --git a/net/core/netprio_cgroup.c b/net/core/netprio_cgroup.c
index aa907ed..3e953ea 100644
--- a/net/core/netprio_cgroup.c
+++ b/net/core/netprio_cgroup.c
@@ -142,7 +142,7 @@ 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();
@@ -166,7 +166,7 @@ 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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