From: Nikolay Aleksandrov <nikolay@redhat.com>
Date: Thu, 19 Sep 2013 13:02:35 +0000 (+0200)
Subject: netpoll: fix NULL pointer dereference in netpoll_cleanup
X-Git-Tag: v3.2.52~48
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=2eb90b30797b3c908b597e4a2a700d6ef9ae0196;p=pandora-kernel.git

netpoll: fix NULL pointer dereference in netpoll_cleanup

[ Upstream commit d0fe8c888b1fd1a2f84b9962cabcb98a70988aec ]

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>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---

Reading git-diff-tree failed