[ 02/80] bonding: fix race condition in bonding_store_slaves_active

Greg Kroah-Hartman
2013-01-09T21:51:18Z

From: "nikolay@redhat.com" <nikolay@redhat.com>

[ Upstream commit e196c0e579902f42cf72414461fb034e5a1ffbf7 ]

Race between bonding_store_slaves_active() and slave manipulation
functions. The bond_for_each_slave use in bonding_store_slaves_active()
is not protected by any synchronization mechanism.
NULL pointer dereference is easy to reach.
Fixed by acquiring the bond->lock for the slave walk.

v2: Make description text < 75 columns

Signed-off-by: Nikolay Aleksandrov <nikolay@redhat.com>
Signed-off-by: Jay Vosburgh <fubar@us.ibm.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 | 2 ++
1 file changed, 2 insertions(+)

--- a/drivers/net/bonding/bond_sysfs.c
+++ b/drivers/net/bonding/bond_sysfs.c
@@ -1578,6 +1578,7 @@ static ssize_t bonding_store_slaves_acti
goto out;
}

+ read_lock(&bond->lock);
bond_for_each_slave(bond, slave, i) {
if (!bond_is_active_slave(slave)) {
if (new_value)
@@ -1586,6 +1587,7 @@ static ssize_t bonding_store_slaves_acti
slave->inactive = 1;
}
}
+ read_unlock(&bond->lock);
out:
return ret;
}