From: Arun Ramadoss <arun.ramadoss@xxxxxxxxxxxxx>
commit ef1100ef20f29aec4e62abeccdb5bdbebba1e378 upstream.
When the ksz module is installed and removed using rmmod, kernel crashes
with null pointer dereferrence error. During rmmod, ksz_switch_remove
function tries to cancel the mib_read_workqueue using
cancel_delayed_work_sync routine and unregister switch from dsa.
During dsa_unregister_switch it calls ksz_mac_link_down, which in turn
reschedules the workqueue since mib_interval is non-zero.
Due to which queue executed after mib_interval and it tries to access
dp->slave. But the slave is unregistered in the ksz_switch_remove
function. Hence kernel crashes.
To avoid this crash, before canceling the workqueue, resetted the
mib_interval to 0.
v1 -> v2:
-Removed the if condition in ksz_mib_read_work
Fixes: 469b390e1ba3 ("net: dsa: microchip: use delayed_work instead of timer + work")
Signed-off-by: Arun Ramadoss <arun.ramadoss@xxxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/net/dsa/microchip/ksz_common.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
--- a/drivers/net/dsa/microchip/ksz_common.c
+++ b/drivers/net/dsa/microchip/ksz_common.c
@@ -460,8 +460,10 @@ EXPORT_SYMBOL(ksz_switch_register);
void ksz_switch_remove(struct ksz_device *dev)
{
/* timer started */
- if (dev->mib_read_interval)
+ if (dev->mib_read_interval) {
+ dev->mib_read_interval = 0;
cancel_delayed_work_sync(&dev->mib_read);
+ }
dev->dev_ops->exit(dev);
dsa_unregister_switch(dev->ds);
