[Bridge] [PATCH] net: bridge: add missing NULL checks

[Nikolay Aleksandrov]

br_port_get_rtnl() can return NULL
---
net/bridge/br_netlink.c | 12 ++++++++++--
1 file changed, 10 insertions(+), 2 deletions(-)

Nacked-by: Nikolay Aleksandrov <***@cumulusnetworks.com>
More below.

diff --git a/net/bridge/br_netlink.c b/net/bridge/br_netlink.c
index 015f465c..cbec11f 100644
--- a/net/bridge/br_netlink.c
+++ b/net/bridge/br_netlink.c
@@ -939,14 +939,17 @@ static int br_port_slave_changelink(struct net_device *brdev,
struct nlattr *data[],
struct netlink_ext_ack *extack)
{
+ struct net_bridge_port *port = br_port_get_rtnl(dev);
struct net_bridge *br = netdev_priv(brdev);
int ret;
if (!data)
return 0;
+ if (!port)
+ return -EINVAL;

If we're here, it means the master device of dev is a bridge => dev is a bridge port,
since we're running with RTNL that cannot change, so this check is unnecessary.

Have you actually hit a bug with this code ?

spin_lock_bh(&br->lock);
- ret = br_setport(br_port_get_rtnl(dev), data);
+ ret = br_setport(port, data);
spin_unlock_bh(&br->lock);
return ret;
@@ -956,7 +959,12 @@ static int br_port_fill_slave_info(struct sk_buff *skb,
const struct net_device *brdev,
const struct net_device *dev)
{
- return br_port_fill_attrs(skb, br_port_get_rtnl(dev));
+ struct net_bridge_port *port = br_port_get_rtnl(dev);
+
+ if (!port)
+ return -EINVAL;
+
+ return br_port_fill_attrs(skb, port);

Same rationale here, fill_slave_info is called via a master device's ops
under RTNL, which means dev is a bridge port and that also cannot change.

If you have hit a bug with this code, can we see the trace ?
The problem might be elsewhere.

Thanks,
Nik

}
static size_t br_port_get_slave_size(const struct net_device *brdev,

[Laszlo Toth]

Post by Nikolay Aleksandrov

br_port_get_rtnl() can return NULL
---
net/bridge/br_netlink.c | 12 ++++++++++--
1 file changed, 10 insertions(+), 2 deletions(-)

More below.

diff --git a/net/bridge/br_netlink.c b/net/bridge/br_netlink.c
index 015f465c..cbec11f 100644
--- a/net/bridge/br_netlink.c
+++ b/net/bridge/br_netlink.c
@@ -939,14 +939,17 @@ static int br_port_slave_changelink(struct net_device *brdev,
struct nlattr *data[],
struct netlink_ext_ack *extack)
{
+ struct net_bridge_port *port = br_port_get_rtnl(dev);
struct net_bridge *br = netdev_priv(brdev);
int ret;
if (!data)
return 0;
+ if (!port)
+ return -EINVAL;

If we're here, it means the master device of dev is a bridge => dev is a bridge port,
since we're running with RTNL that cannot change, so this check is unnecessary.
Have you actually hit a bug with this code ?

spin_lock_bh(&br->lock);
- ret = br_setport(br_port_get_rtnl(dev), data);
+ ret = br_setport(port, data);
spin_unlock_bh(&br->lock);
return ret;
@@ -956,7 +959,12 @@ static int br_port_fill_slave_info(struct sk_buff *skb,
const struct net_device *brdev,
const struct net_device *dev)
{
- return br_port_fill_attrs(skb, br_port_get_rtnl(dev));
+ struct net_bridge_port *port = br_port_get_rtnl(dev);
+
+ if (!port)
+ return -EINVAL;
+
+ return br_port_fill_attrs(skb, port);

Same rationale here, fill_slave_info is called via a master device's ops
under RTNL, which means dev is a bridge port and that also cannot change.
If you have hit a bug with this code, can we see the trace ?
The problem might be elsewhere.

There was a NULL dereference in br_port_fill_attrs(), but on a much
older release w/ a probably buggy and custom driver,
so there is no real problem to trace.
Anyway I thought I'd make a quick patch from it, but you're right,
it's pointless to validate twice.

Please just ignore the patch.

Laszlo

Post by Nikolay Aleksandrov
Thanks,
Nik

}
static size_t br_port_get_slave_size(const struct net_device *brdev,