The following commit has been merged in the batadv/lts/5.4 branch: commit 34a600f861b038f3c821e10a59c31f3f14e94bcc Author: Sven Eckelmann sven@narfation.org Date: Mon Feb 28 00:01:24 2022 +0100

batman-adv: Request iflink once in batadv_get_real_netdevice

commit 6116ba09423f7d140f0460be6a1644dceaad00da upstream.

There is no need to call dev_get_iflink multiple times for the same net_device in batadv_get_real_netdevice. And since some of the ndo_get_iflink callbacks are dynamic (for example via RCUs like in vxcan_get_iflink), it could easily happen that the returned values are not stable. The pre-checks before __dev_get_by_index are then of course bogus.

Fixes: 5ed4a460a1d3 ("batman-adv: additional checks for virtual interfaces on top of WiFi") Signed-off-by: Sven Eckelmann sven@narfation.org Signed-off-by: Simon Wunderlich sw@simonwunderlich.de

diff --git a/net/batman-adv/hard-interface.c b/net/batman-adv/hard-interface.c index e898959b282e..d896208775db 100644 --- a/net/batman-adv/hard-interface.c +++ b/net/batman-adv/hard-interface.c @@ -217,14 +217,16 @@ static struct net_device *batadv_get_real_netdevice(struct net_device *netdev) struct net_device *real_netdev = NULL; struct net *real_net; struct net *net; - int ifindex; + int iflink;

ASSERT_RTNL();

if (!netdev) return NULL;

- if (netdev->ifindex == dev_get_iflink(netdev)) { + iflink = dev_get_iflink(netdev); + + if (netdev->ifindex == iflink) { dev_hold(netdev); return netdev; } @@ -234,9 +236,8 @@ static struct net_device *batadv_get_real_netdevice(struct net_device *netdev) goto out;

net = dev_net(hard_iface->soft_iface); - ifindex = dev_get_iflink(netdev); real_net = batadv_getlink_net(netdev, net); - real_netdev = dev_get_by_index(real_net, ifindex); + real_netdev = dev_get_by_index(real_net, iflink);

out: if (hard_iface)