macvlan: add cond_resched() during multicast processing

[ Upstream commit 62c096d2f6639a7ef20ebc4530f57bd100af967f ]

The Rx bound multicast packets are deferred to a workqueue and
macvlan can also suffer from the same attack that was discovered
by Syzbot for IPvlan. This solution is not as effective as in
IPvlan. IPvlan defers all (Tx and Rx) multicast packet processing
to a workqueue while macvlan does this way only for the Rx. This
fix should address the Rx codition to certain extent.

Tx is still suseptible. Tx multicast processing happens when
.ndo_start_xmit is called, hence we cannot add cond_resched().
However, it's not that severe since the user which is generating
 / flooding will be affected the most.

Fixes: 3befbe94a40a ("macvlan: Move broadcasts into a work queue")
Signed-off-by: Mahesh Bandewar <maheshb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/net/macvlan.c b/drivers/net/macvlan.c
index c5bf61565726b15aa1ea63590d7d8627b0c20d4a..26f6be4796c7535766c93272755b3876d17f8f11 100644 (file)
--- a/drivers/net/macvlan.c
+++ b/drivers/net/macvlan.c
@@ -334,6 +334,8 @@ static void macvlan_process_broadcast(struct work_struct *w)
                if (src)
                        dev_put(src->dev);
                consume_skb(skb);
+
+               cond_resched();
        }
 }