From: Sven Eckelmann Date: Sun, 30 Dec 2018 11:46:01 +0000 (+0100) Subject: batman-adv: Avoid WARN on net_device without parent in netns X-Git-Tag: v3.18.135~21 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=863938b84c4b2c34623c76dd838014e011951ccc;p=thirdparty%2Fkernel%2Fstable.git batman-adv: Avoid WARN on net_device without parent in netns commit 955d3411a17f590364238bd0d3329b61f20c1cd2 upstream. 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: b7eddd0b3950 ("batman-adv: prevent using any virtual device created on batman-adv as hard-interface") Reported-by: syzbot+c764de0fcfadca9a8595@syzkaller.appspotmail.com Reported-by: Dmitry Vyukov Signed-off-by: Sven Eckelmann Signed-off-by: Simon Wunderlich Signed-off-by: Greg Kroah-Hartman --- diff --git a/net/batman-adv/hard-interface.c b/net/batman-adv/hard-interface.c index fbda6b54baffc..51f060df64ef6 100644 --- a/net/batman-adv/hard-interface.c +++ b/net/batman-adv/hard-interface.c @@ -89,8 +89,10 @@ static bool batadv_is_on_batman_iface(const struct net_device *net_dev) /* recurse over the parent device */ parent_dev = __dev_get_by_index(&init_net, net_dev->iflink); /* 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; + } ret = batadv_is_on_batman_iface(parent_dev);