queue-5.0/net-bridge-multicast-use-rcu-to-access-port-list-from-br_multicast_start_querier.patch

   1 From foo@baz Sat Apr 20 16:43:09 CEST 2019
   2 From: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
   3 Date: Thu, 11 Apr 2019 15:08:25 +0300
   4 Subject: net: bridge: multicast: use rcu to access port list from br_multicast_start_querier
   5
   6 From: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
   7
   8 [ Upstream commit c5b493ce192bd7a4e7bd073b5685aad121eeef82 ]
   9
  10 br_multicast_start_querier() walks over the port list but it can be
  11 called from a timer with only multicast_lock held which doesn't protect
  12 the port list, so use RCU to walk over it.
  13
  14 Fixes: c83b8fab06fc ("bridge: Restart queries when last querier expires")
  15 Signed-off-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
  16 Signed-off-by: David S. Miller <davem@davemloft.net>
  17 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  18 ---
  19  net/bridge/br_multicast.c |    4 +++-
  20  1 file changed, 3 insertions(+), 1 deletion(-)
  21
  22 --- a/net/bridge/br_multicast.c
  23 +++ b/net/bridge/br_multicast.c
  24 @@ -1916,7 +1916,8 @@ static void br_multicast_start_querier(s
  25
  26         __br_multicast_open(br, query);
  27
  28 -       list_for_each_entry(port, &br->port_list, list) {
  29 +       rcu_read_lock();
  30 +       list_for_each_entry_rcu(port, &br->port_list, list) {
  31                 if (port->state == BR_STATE_DISABLED ||
  32                     port->state == BR_STATE_BLOCKING)
  33                         continue;
  34 @@ -1928,6 +1929,7 @@ static void br_multicast_start_querier(s
  35                         br_multicast_enable(&port->ip6_own_query);
  36  #endif
  37         }
  38 +       rcu_read_unlock();
  39  }
  40
  41  int br_multicast_toggle(struct net_bridge *br, unsigned long val)