[PATCH 3.12 18/83] bonding: fix two race conditions in bond_store_updelay/downdelay

Greg Kroah-Hartman
2013-12-06T21:52:35Z

From: Nikolay Aleksandrov <nikolay@redhat.com>

[ Upstream commit b869ccfab1e324507fa3596e3e1308444fb68227 ]

This patch fixes two race conditions between bond_store_updelay/downdelay
and bond_store_miimon which could lead to division by zero as miimon can
be set to 0 while either updelay/downdelay are being set and thus miss the
zero check in the beginning, the zero div happens because updelay/downdelay
are stored as new_value / bond->params.miimon. Use rtnl to synchronize with
miimon setting.

CC: Jay Vosburgh <fubar@us.ibm.com>
CC: Andy Gospodarek <andy@greyhouse.net>
CC: Veaceslav Falico <vfalico@redhat.com>
Signed-off-by: Nikolay Aleksandrov <nikolay@redhat.com>
Acked-by: Veaceslav Falico <vfalico@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/net/bonding/bond_sysfs.c | 6 ++++++
1 file changed, 6 insertions(+)

--- a/drivers/net/bonding/bond_sysfs.c
+++ b/drivers/net/bonding/bond_sysfs.c
@@ -760,6 +760,8 @@ static ssize_t bonding_store_downdelay(s
int new_value, ret = count;
struct bonding *bond = to_bond(d);

+ if (!rtnl_trylock())
+ return restart_syscall();
if (!(bond->params.miimon)) {
pr_err("%s: Unable to set down delay as MII monitoring is disabled\n",
bond->dev->name);
@@ -793,6 +795,7 @@ static ssize_t bonding_store_downdelay(s
}

out:
+ rtnl_unlock();
return ret;
}
static DEVICE_ATTR(downdelay, S_IRUGO | S_IWUSR,
@@ -815,6 +818,8 @@ static ssize_t bonding_store_updelay(str
int new_value, ret = count;
struct bonding *bond = to_bond(d);

+ if (!rtnl_trylock())
+ return restart_syscall();
if (!(bond->params.miimon)) {
pr_err("%s: Unable to set up delay as MII monitoring is disabled\n",
bond->dev->name);
@@ -848,6 +853,7 @@ static ssize_t bonding_store_updelay(str
}

out:
+ rtnl_unlock();
return ret;
}
static DEVICE_ATTR(updelay, S_IRUGO | S_IWUSR,