On 10/5/2020 9:08 AM, Christian Eggers wrote:
Between queuing the delayed work and finishing the setup of the dsa
ports, the process may sleep in request_module() and the queued work may
be executed prior the initialization of the DSA ports is finished. 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() make 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().
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.
Signed-off-by: Christian Eggers <ceggers@xxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
This looks fine to me and the analysis appears to be correct, don't you
need to pair the test for dev->mib_read_internal being non zero with
setting it to zero in ksz_switch_unregister()?
You would also most likely want to add a Fixes: tag such that this can
be back ported to stable trees?
---
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 */
static void ksz_mib_read_work()
\--netif_carrier_ok(dp->slave); dp->slave has not been initialized yet
drivers/net/dsa/microchip/ksz_common.c | 16 +++++++++-------
1 file changed, 9 insertions(+), 7 deletions(-)
diff --git a/drivers/net/dsa/microchip/ksz_common.c b/drivers/net/dsa/microchip/ksz_common.c
index 8e755b50c9c1..a94d2278b95c 100644
--- 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_device *dev)
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);
@@ -143,7 +137,9 @@ void ksz_mac_link_down(struct dsa_switch *ds, int port, unsigned int mode,
/* Read all MIB counters when the link is going down. */
p->read = true;
- schedule_delayed_work(&dev->mib_read, 0);
+ /* timer started */
+ if (dev->mib_read_interval)
+ schedule_delayed_work(&dev->mib_read, 0);
}
EXPORT_SYMBOL_GPL(ksz_mac_link_down);
@@ -446,6 +442,12 @@ int ksz_switch_register(struct ksz_device *dev,
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);
--
Florian
