tree 0d148e7dfea45c04842617aa32c9be50235d606a
parent c194992cbe71c20bb3623a566af8d11b0bfaa721
author Nikolay Aleksandrov <nikolay@redhat.com> 1379595755 +0200
committer David S. Miller <davem@davemloft.net> 1379614553 -0400

netpoll: fix NULL pointer dereference in netpoll_cleanup

I've been hitting a NULL ptr deref while using netconsole because the
np->dev check and the pointer manipulation in netpoll_cleanup are done
without rtnl and the following sequence happens when having a netconsole
over a vlan and we remove the vlan while disabling the netconsole:
	CPU 1					CPU2
					removes vlan and calls the notifier
enters store_enabled(), calls
netdev_cleanup which checks np->dev
and then waits for rtnl
					executes the netconsole netdev
					release notifier making np->dev
					== NULL and releases rtnl
continues to dereference a member of
np->dev which at this point is == NULL

Signed-off-by: Nikolay Aleksandrov <nikolay@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>