commit 690bb6fb64f5dc7437317153902573ecad67593d upstream.
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: b7eddd0b3950 ("batman-adv: prevent using any virtual device created on batman-adv as hard-interface")
Signed-off-by: Sven Eckelmann <sven@xxxxxxxxxxxxx>
Signed-off-by: Simon Wunderlich <sw@xxxxxxxxxxxxxxxxxx>
[ bp: 4.9 backported: adjust context. ]
Signed-off-by: Sven Eckelmann <sven@xxxxxxxxxxxxx>
---
net/batman-adv/hard-interface.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)
diff --git a/net/batman-adv/hard-interface.c b/net/batman-adv/hard-interface.c
index 4f384abb4ced..64cf9cd3be4d 100644
--- a/net/batman-adv/hard-interface.c
+++ b/net/batman-adv/hard-interface.c
@@ -155,22 +155,23 @@ 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;
const 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");
--
2.30.2
