From: Mahesh Bandewar maheshb@google.com
[ Upstream commit ce9a4186f9ac475c415ffd20348176a4ea366670 ]
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: 412ca1550cbe ("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 --- drivers/net/macvlan.c | 2 ++ 1 file changed, 2 insertions(+)
--- a/drivers/net/macvlan.c +++ b/drivers/net/macvlan.c @@ -306,6 +306,8 @@ static void macvlan_process_broadcast(st rcu_read_unlock();
kfree_skb(skb); + + cond_resched(); } }