From: Christian Eggers ceggers@arri.de
[ Upstream commit 8098bd69bc4e925070313b1b95d03510f4f24738 ]
Between queuing the delayed work and finishing the setup of the dsa ports, the process may sleep in request_module() (via phy_device_create()) and the queued work may be executed prior to the switch net devices being registered. In ksz_mib_read_work(), a NULL dereference will happen within netof_carrier_ok(dp->slave).
Not queuing the delayed work in ksz_init_mib_timer() makes things even worse because the work will now be queued for immediate execution (instead of 2000 ms) in ksz_mac_link_down() via dsa_port_link_register_of().
Call tree: ksz9477_i2c_probe() --ksz9477_switch_register() --ksz_switch_register() +--dsa_register_switch() | --dsa_switch_probe() | --dsa_tree_setup() | --dsa_tree_setup_switches() | +--dsa_switch_setup() | | +--ksz9477_setup() | | | --ksz_init_mib_timer() | | | |--/* Start the timer 2 seconds later. */ | | | --schedule_delayed_work(&dev->mib_read, msecs_to_jiffies(2000)); | | --__mdiobus_register() | | --mdiobus_scan() | | --get_phy_device() | | +--get_phy_id() | | --phy_device_create() | | |--/* sleeping, ksz_mib_read_work() can be called meanwhile */ | | --request_module() | | | --dsa_port_setup() | +--/* Called for non-CPU ports */ | +--dsa_slave_create() | | +--/* Too late, ksz_mib_read_work() may be called beforehand */ | | --port->slave = ... | ... | +--Called for CPU port */ | --dsa_port_link_register_of() | --ksz_mac_link_down() | +--/* mib_read must be initialized here */ | +--/* work is already scheduled, so it will be executed after 2000 ms */ | --schedule_delayed_work(&dev->mib_read, 0); -- /* here port->slave is setup properly, scheduling the delayed work should be safe */
Solution: 1. Do not queue (only initialize) delayed work in ksz_init_mib_timer(). 2. Only queue delayed work in ksz_mac_link_down() if init is completed. 3. Queue work once in ksz_switch_register(), after dsa_register_switch() has completed.
Fixes: 7c6ff470aa86 ("net: dsa: microchip: add MIB counter reading support") Signed-off-by: Christian Eggers ceggers@arri.de Reviewed-by: Florian Fainelli f.fainelli@gmail.com Reviewed-by: Vladimir Oltean olteanv@gmail.com Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/net/dsa/microchip/ksz_common.c | 16 +++++++++------- 1 file changed, 9 insertions(+), 7 deletions(-)
--- a/drivers/net/dsa/microchip/ksz_common.c +++ b/drivers/net/dsa/microchip/ksz_common.c @@ -103,14 +103,8 @@ void ksz_init_mib_timer(struct ksz_devic
INIT_DELAYED_WORK(&dev->mib_read, ksz_mib_read_work);
- /* Read MIB counters every 30 seconds to avoid overflow. */ - dev->mib_read_interval = msecs_to_jiffies(30000); - for (i = 0; i < dev->mib_port_cnt; i++) dev->dev_ops->port_init_cnt(dev, i); - - /* Start the timer 2 seconds later. */ - schedule_delayed_work(&dev->mib_read, msecs_to_jiffies(2000)); } EXPORT_SYMBOL_GPL(ksz_init_mib_timer);
@@ -144,7 +138,9 @@ void ksz_adjust_link(struct dsa_switch * /* Read all MIB counters when the link is going down. */ if (!phydev->link) { p->read = true; - schedule_delayed_work(&dev->mib_read, 0); + /* timer started */ + if (dev->mib_read_interval) + schedule_delayed_work(&dev->mib_read, 0); } mutex_lock(&dev->dev_mutex); if (!phydev->link) @@ -460,6 +456,12 @@ int ksz_switch_register(struct ksz_devic return ret; }
+ /* Read MIB counters every 30 seconds to avoid overflow. */ + dev->mib_read_interval = msecs_to_jiffies(30000); + + /* Start the MIB timer. */ + schedule_delayed_work(&dev->mib_read, 0); + return 0; } EXPORT_SYMBOL(ksz_switch_register);