[commits] [batman-adv] master: batman-adv: Avoid WARN on net_device without parent in netns (59ad0440)

postmaster at open-mesh.org postmaster at open-mesh.org
Fri Jan 4 11:09:05 CET 2019

Repository : ssh://git@open-mesh.org/batman-adv

On branch  : master


commit 59ad04405be86f648fd83d81d2fd0a78f215a43b
Author: Sven Eckelmann <sven at narfation.org>
Date:   Sun Dec 30 12:46:01 2018 +0100

    batman-adv: Avoid WARN on net_device without parent in netns
    It is not allowed to use WARN* helpers on potential incorrect input from
    the user or transient problems because systems configured as panic_on_warn
    will reboot due to such a problem.
    A NULL return value of __dev_get_by_index can be caused by various problems
    which can either be related to the system configuration or problems
    (incorrectly returned network namespaces) in other (virtual) net_device
    drivers. batman-adv should not cause a (harmful) WARN in this situation and
    instead only report it via a simple message.
    Fixes: 3d48811b27f5 ("batman-adv: prevent using any virtual device created on batman-adv as hard-interface")
    Reported-by: syzbot+c764de0fcfadca9a8595 at syzkaller.appspotmail.com
    Reported-by: Dmitry Vyukov <dvyukov at google.com>
    Signed-off-by: Sven Eckelmann <sven at narfation.org>


 net/batman-adv/hard-interface.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/net/batman-adv/hard-interface.c b/net/batman-adv/hard-interface.c
index 781c5b6e..41be60d5 100644
--- a/net/batman-adv/hard-interface.c
+++ b/net/batman-adv/hard-interface.c
@@ -20,7 +20,6 @@
 #include "main.h"
 #include <linux/atomic.h>
-#include <linux/bug.h>
 #include <linux/byteorder/generic.h>
 #include <linux/errno.h>
 #include <linux/gfp.h>
@@ -179,8 +178,10 @@ static bool batadv_is_on_batman_iface(const struct net_device *net_dev)
 	parent_dev = __dev_get_by_index((struct net *)parent_net,
 	/* if we got a NULL parent_dev there is something broken.. */
-	if (WARN(!parent_dev, "Cannot find parent device"))
+	if (!parent_dev) {
+		pr_err("Cannot find parent device\n");
 		return false;
+	}
 	if (batadv_mutual_parents(net_dev, net, parent_dev, parent_net))
 		return false;

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