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From: Simon Wunderlich <sw@simonwunderlich.de>
To: davem@davemloft.net, kuba@kernel.org
Cc: netdev@vger.kernel.org, b.a.t.m.a.n@lists.open-mesh.org,
	Sven Eckelmann <sven@narfation.org>,
	Simon Wunderlich <sw@simonwunderlich.de>
Subject: [PATCH 1/3] batman-adv: Request iflink once in batadv-on-batadv check
Date: Wed,  2 Mar 2022 17:30:47 +0100	[thread overview]
Message-ID: <20220302163049.101957-2-sw@simonwunderlich.de> (raw)
In-Reply-To: <20220302163049.101957-1-sw@simonwunderlich.de>

From: Sven Eckelmann <sven@narfation.org>

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@narfation.org>
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>
---
 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 8a2b78f9c4b2..35aa1122043b 100644
--- a/net/batman-adv/hard-interface.c
+++ b/net/batman-adv/hard-interface.c
@@ -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");
-- 
2.30.2


  reply	other threads:[~2022-03-02 16:30 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-03-02 16:30 [PATCH 0/3] pull request for net: batman-adv 2022-03-02 Simon Wunderlich
2022-03-02 16:30 ` Simon Wunderlich [this message]
2022-03-03  6:00   ` [PATCH 1/3] batman-adv: Request iflink once in batadv-on-batadv check patchwork-bot+netdevbpf
2022-03-02 16:30 ` [PATCH 2/3] batman-adv: Request iflink once in batadv_get_real_netdevice Simon Wunderlich
2022-03-02 16:30 ` [PATCH 3/3] batman-adv: Don't expect inter-netns unique iflink indices Simon Wunderlich

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