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authorNikolay Aleksandrov <nikolay@redhat.com>2013-09-19 15:02:35 +0200
committerDavid S. Miller <davem@davemloft.net>2013-09-19 14:15:53 -0400
commitd0fe8c888b1fd1a2f84b9962cabcb98a70988aec (patch)
tree0d148e7dfea45c04842617aa32c9be50235d606a /net
parentc194992cbe71c20bb3623a566af8d11b0bfaa721 (diff)
downloadlinux-linaro-stable-d0fe8c888b1fd1a2f84b9962cabcb98a70988aec.tar.gz
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>
Diffstat (limited to 'net')
-rw-r--r--net/core/netpoll.c9
1 files changed, 4 insertions, 5 deletions
diff --git a/net/core/netpoll.c b/net/core/netpoll.c
index c3c7b27c112d..fc75c9e461b8 100644
--- a/net/core/netpoll.c
+++ b/net/core/netpoll.c
@@ -1284,15 +1284,14 @@ EXPORT_SYMBOL_GPL(__netpoll_free_async);
void netpoll_cleanup(struct netpoll *np)
{
- if (!np->dev)
- return;
-
rtnl_lock();
+ if (!np->dev)
+ goto out;
__netpoll_cleanup(np);
- rtnl_unlock();
-
dev_put(np->dev);
np->dev = NULL;
+out:
+ rtnl_unlock();
}
EXPORT_SYMBOL(netpoll_cleanup);