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net: dsa: microchip: Added the condition for scheduling ksz_mib_read_work

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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: 469b390e1b ("net: dsa: microchip: use delayed_work instead of timer + work")
Signed-off-by: Arun Ramadoss <arun.ramadoss@microchip.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Arun Ramadoss 2021-10-11 21:18:08 +05:30 committed by David S. Miller
parent 9973a43012
commit ef1100ef20
1 changed files with 3 additions and 1 deletions
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4
drivers/net/dsa/microchip/ksz_common.c
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@ -449,8 +449,10 @@ 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);