Commit d8b2a4d2 authored Feb 12, 2008 by Matti Linnanvuori Committed by David S. Miller Feb 12, 2008

[NET]: Fix race in dev_close(). (Bug 9750)



There is a race in Linux kernel file net/core/dev.c, function dev_close.
The function calls function dev_deactivate, which calls function
dev_watchdog_down that deletes the watchdog timer. However, after that, a
driver can call netif_carrier_ok, which calls function
__netdev_watchdog_up that can add the watchdog timer again. Function
unregister_netdevice calls function dev_shutdown that traps the bug
!timer_pending(&dev->watchdog_timer). Moving dev_deactivate after
netif_running() has been cleared prevents function netif_carrier_on
from calling __netdev_watchdog_up and adding the watchdog timer again.

Signed-off-by: Matti Linnanvuori <mattilinnanvuori@yahoo.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent b318e0e4

net/core/dev.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -1071,8 +1071,6 @@ int dev_close(struct net_device *dev)
		*/
		call_netdevice_notifiers(NETDEV_GOING_DOWN, dev);

		dev_deactivate(dev);

		clear_bit(__LINK_STATE_START, &dev->state);

		/* Synchronize to scheduled poll. We cannot touch poll list,
		@@ -1083,6 +1081,8 @@ int dev_close(struct net_device *dev)
		*/
		smp_mb__after_clear_bit(); /* Commit netif_running(). */

		dev_deactivate(dev);

		/*
		* Call the device specific close. This cannot fail.
		* Only if device is UP

Admin message