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batman-adv: Request iflink once in batadv_get_real_netdevice

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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: 5ed4a460a1 ("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>
This commit is contained in:
Sven Eckelmann
2022-02-28 00:01:24 +01:00
committed by Greg Kroah-Hartman
parent dcf10d78ff
commit 3dae11d21f
1 changed files with 5 additions and 4 deletions
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9
net/batman-adv/hard-interface.c
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@@ -217,14 +217,16 @@ static struct net_device *batadv_get_real_netdevice(struct net_device *netdev)
struct net_device *real_netdev = NULL; struct net_device *real_netdev = NULL;
struct net *real_net; struct net *real_net;
struct net *net; struct net *net;
int ifindex; int iflink;
ASSERT_RTNL(); ASSERT_RTNL();
if (!netdev) if (!netdev)
return NULL; return NULL;
if (netdev->ifindex == dev_get_iflink(netdev)) { iflink = dev_get_iflink(netdev);
if (netdev->ifindex == iflink) {
dev_hold(netdev); dev_hold(netdev);
return netdev; return netdev;
} }
@@ -234,9 +236,8 @@ static struct net_device *batadv_get_real_netdevice(struct net_device *netdev)
goto out; goto out;
net = dev_net(hard_iface->soft_iface); net = dev_net(hard_iface->soft_iface);
ifindex = dev_get_iflink(netdev);
real_net = batadv_getlink_net(netdev, net); 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: out:
if (hard_iface) if (hard_iface)