| From | Kamal Mostafa <> | Subject | [PATCH 3.8 36/81] netpoll: fix NULL pointer dereference in netpoll_cleanup | Date | Tue, 29 Oct 2013 11:03:57 -0700 |
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3.8.13.12 -stable review patch. If anyone has any objections, please let me know.
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From: Nikolay Aleksandrov <nikolay@redhat.com>
[ 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: Kamal Mostafa <kamal@canonical.com> --- net/core/netpoll.c | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-)
diff --git a/net/core/netpoll.c b/net/core/netpoll.c index 3151acf..40c1496 100644 --- a/net/core/netpoll.c +++ b/net/core/netpoll.c @@ -962,15 +962,14 @@ EXPORT_SYMBOL_GPL(__netpoll_free_rcu); 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); -- 1.8.1.2
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