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batman-adv: Request iflink once in batadv-on-batadv check

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There is no need to call dev_get_iflink multiple times for the same
net_device in batadv_is_on_batman_iface. 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: b7eddd0b39 ("batman-adv: prevent using any virtual device created on batman-adv as hard-interface")
Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>
This commit is contained in:
Sven Eckelmann 2022-02-28 00:01:24 +01:00 committed by Simon Wunderlich
parent e783362eb5
commit 690bb6fb64
1 changed files with 5 additions and 4 deletions
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9
net/batman-adv/hard-interface.c
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@ -149,22 +149,23 @@ static bool batadv_is_on_batman_iface(const struct net_device *net_dev)
struct net *net = dev_net(net_dev);
struct net_device *parent_dev;
struct net *parent_net;
int iflink;
bool ret;
/* check if this is a batman-adv mesh interface */
if (batadv_softif_is_valid(net_dev))
return true;
iflink = dev_get_iflink(net_dev);
/* no more parents..stop recursion */
if (dev_get_iflink(net_dev) == 0 ||
dev_get_iflink(net_dev) == net_dev->ifindex)
if (iflink == 0 || iflink == net_dev->ifindex)
return false;
parent_net = batadv_getlink_net(net_dev, net);
/* recurse over the parent device */
parent_dev = __dev_get_by_index((struct net *)parent_net,
dev_get_iflink(net_dev));
parent_dev = __dev_get_by_index((struct net *)parent_net, iflink);
/* if we got a NULL parent_dev there is something broken.. */
if (!parent_dev) {
pr_err("Cannot find parent device\n");