Commit 130ec90c authored Feb 28, 2022 by Sven Eckelmann Committed by Greg Kroah-Hartman Mar 08, 2022

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: 5ed4a460 ("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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent 86b66abc

net/batman-adv/hard-interface.c

+5 −4

Original line number	Diff line number	Diff line
		@@ -228,14 +228,16 @@ 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;
		}
		@@ -245,9 +247,8 @@ 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)