netdev - [PATCH] ieee802154: check device type

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Date:	Wed, 20 Jul 2016 10:43:11 +0200
From:	Vegard Nossum <vegard.nossum@...cle.com>
To:	Alexander Aring <aar@...gutronix.de>
Cc:	linux-wpan@...r.kernel.org, netdev@...r.kernel.org,
	Vegard Nossum <vegard.nossum@...cle.com>,
	Lennert Buytenhek <buytenh@...tstofly.org>,
	Alexander Aring <alex.aring@...il.com>,
	Marcel Holtmann <marcel@...tmann.org>,
	Dmitry Eremin-Solenikov <dbaryshkov@...il.com>,
	Sergey Lapin <slapin@...fans.org>
Subject: [PATCH] ieee802154: check device type

I've observed a NULL pointer dereference in ieee802154_del_iface() during
netlink fuzzing. It's the ->wpan_phy dereference here:

        phy = dev->ieee802154_ptr->wpan_phy;

My bet is that we're not checking that this is an IEEE802154 interface,
so let's do what ieee802154_nl_get_dev() is doing. (Maybe we should even
be calling this directly?)

Cc: Lennert Buytenhek <buytenh@...tstofly.org>
Cc: Alexander Aring <alex.aring@...il.com>
Cc: Marcel Holtmann <marcel@...tmann.org>
Cc: Dmitry Eremin-Solenikov <dbaryshkov@...il.com>
Cc: Sergey Lapin <slapin@...fans.org>
Signed-off-by: Vegard Nossum <vegard.nossum@...cle.com>
---
 net/ieee802154/nl-phy.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/net/ieee802154/nl-phy.c b/net/ieee802154/nl-phy.c
index 77d7301..dc2960b 100644
--- a/net/ieee802154/nl-phy.c
+++ b/net/ieee802154/nl-phy.c
@@ -286,9 +286,12 @@ int ieee802154_del_iface(struct sk_buff *skb, struct genl_info *info)
 	if (name[nla_len(info->attrs[IEEE802154_ATTR_DEV_NAME]) - 1] != '\0')
 		return -EINVAL; /* name should be null-terminated */
 
+	rc = -ENODEV;
 	dev = dev_get_by_name(genl_info_net(info), name);
 	if (!dev)
-		return -ENODEV;
+		return rc;
+	if (dev->type != ARPHRD_IEEE802154)
+		goto out;
 
 	phy = dev->ieee802154_ptr->wpan_phy;
 	BUG_ON(!phy);
@@ -342,6 +345,7 @@ nla_put_failure:
 	nlmsg_free(msg);
 out_dev:
 	wpan_phy_put(phy);
+out:
 	if (dev)
 		dev_put(dev);
 
-- 
1.9.1