[ 076/143] bonding: fix two race conditions in bond_store_updelay/downdelay

Willy Tarreau
2014-05-12T01:43:13Z

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: Willy Tarreau <w@1wt.eu>
---
drivers/net/bonding/bond_sysfs.c | 6 ++++++
1 file changed, 6 insertions(+)

diff --git a/drivers/net/bonding/bond_sysfs.c b/drivers/net/bonding/bond_sysfs.c
index 8762a27..3666a9a 100644
--- a/drivers/net/bonding/bond_sysfs.c
+++ b/drivers/net/bonding/bond_sysfs.c
@@ -755,6 +755,8 @@ static ssize_t bonding_store_downdelay(struct device *d,
int new_value, ret = count;
struct bonding *bond = to_bond(d);

+ if (!rtnl_trylock())
+ return restart_syscall();
if (!(bond->params.miimon)) {
pr_err(DRV_NAME
": %s: Unable to set down delay as MII monitoring is disabled\n",
@@ -795,6 +797,7 @@ static ssize_t bonding_store_downdelay(struct device *d,
}

out:
+ rtnl_unlock();
return ret;
}
static DEVICE_ATTR(downdelay, S_IRUGO | S_IWUSR,
@@ -817,6 +820,8 @@ static ssize_t bonding_store_updelay(struct device *d,
int new_value, ret = count;
struct bonding *bond = to_bond(d);

+ if (!rtnl_trylock())
+ return restart_syscall();
if (!(bond->params.miimon)) {
pr_err(DRV_NAME
": %s: Unable to set up delay as MII monitoring is disabled\n",
@@ -856,6 +861,7 @@ static ssize_t bonding_store_updelay(struct device *d,
}

out:
+ rtnl_unlock();
return ret;
}
static DEVICE_ATTR(updelay, S_IRUGO | S_IWUSR,
--
1.7.12.2.21.g234cd45.dirty