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| author | Nikolay Aleksandrov <nikolay@redhat.com> | 2013-09-19 15:02:35 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2013-10-13 15:42:47 -0700 |
| commit | a8e02b78193d24a73ccedfed64a0d8f5486b7c3c (patch) | |
| tree | a3be9ef5e280d822cf87b526207660fab0e69508 | |
| parent | a4942e9911a439060c744705178b766cf3ebe51e (diff) | |
| download | lwn-a8e02b78193d24a73ccedfed64a0d8f5486b7c3c.tar.gz lwn-a8e02b78193d24a73ccedfed64a0d8f5486b7c3c.zip | |
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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | net/core/netpoll.c | 9 |
1 files changed, 4 insertions, 5 deletions
diff --git a/net/core/netpoll.c b/net/core/netpoll.c index f9f40b932e4b..5e81c495fde3 100644 --- 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); |