linux-kernel - [PATCH 1/6] netprio_cgroup: fix an off-by-one bug

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Message-ID: <4F28E1D1.900@cn.fujitsu.com>
Date:	Wed, 01 Feb 2012 14:55:13 +0800
From:	Li Zefan <lizf@...fujitsu.com>
To:	David Miller <davem@...emloft.net>
CC:	netdev <netdev@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Cgroups <cgroups@...r.kernel.org>,
	Neil Horman <nhorman@...driver.com>
Subject: [PATCH 1/6] netprio_cgroup: fix an off-by-one bug

  # mount -t cgroup xxx /mnt
  # mkdir /mnt/tmp
  # cat /mnt/tmp/net_prio.ifpriomap
  lo 0
  eth0 0
  virbr0 0
  # echo 'lo 999' > /mnt/tmp/net_prio.ifpriomap
  # cat /mnt/tmp/net_prio.ifpriomap
  lo 999
  eth0 0
  virbr0 4101267344

We got weired output, because we exceeded the boundary of the array.
We may even crash the kernel..

Signed-off-by: Li Zefan <lizf@...fujitsu.com>
---
 net/core/netprio_cgroup.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/net/core/netprio_cgroup.c b/net/core/netprio_cgroup.c
index 3a9fd48..a296cbb 100644
--- a/net/core/netprio_cgroup.c
+++ b/net/core/netprio_cgroup.c
@@ -107,7 +107,7 @@ static void extend_netdev_table(struct net_device *dev, u32 new_len)
 static void update_netdev_tables(void)
 {
 	struct net_device *dev;
-	u32 max_len = atomic_read(&max_prioidx);
+	u32 max_len = atomic_read(&max_prioidx) + 1;
 	struct netprio_map *map;
 
 	rtnl_lock();
-- 
1.7.3.1
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