This is a note to let you know that I've just added the patch titled
netpoll: fix NULL pointer dereference in netpoll_cleanup
to the 3.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
netpoll-fix-null-pointer-dereference-in-netpoll_cleanup.patch
and it can be found in the queue-3.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From dc01c29488bac44cd5b702330c6e3e88073cd598 Mon Sep 17 00:00:00 2001
From: Nikolay Aleksandrov <nikolay@xxxxxxxxxx>
Date: Thu, 19 Sep 2013 15:02:35 +0200
Subject: netpoll: fix NULL pointer dereference in netpoll_cleanup
From: Nikolay Aleksandrov <nikolay@xxxxxxxxxx>
[ 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@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/core/netpoll.c | 9 ++++-----
1 file changed, 4 insertions(+), 5 deletions(-)
--- a/net/core/netpoll.c
+++ b/net/core/netpoll.c
@@ -920,15 +920,14 @@ EXPORT_SYMBOL_GPL(__netpoll_cleanup);
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);
Patches currently in stable-queue which might be from nikolay@xxxxxxxxxx are
queue-3.4/netpoll-fix-null-pointer-dereference-in-netpoll_cleanup.patch
queue-3.4/net-flow_dissector-fix-thoff-for-ipproto_ah.patch
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