netdev - [PATCH net 2/5] vxlan: Don't double-free default FDB entry in __vxlan_dev

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <189ee054f0c5d652801e6df1883ae723e8a934f2.1545057865.git.petrm@mellanox.com>
Date:   Mon, 17 Dec 2018 14:58:44 +0000
From:   Petr Machata <petrm@...lanox.com>
To:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>
CC:     "davem@...emloft.net" <davem@...emloft.net>,
        Ido Schimmel <idosch@...lanox.com>,
        "roopa@...ulusnetworks.com" <roopa@...ulusnetworks.com>
Subject: [PATCH net 2/5] vxlan: Don't double-free default FDB entry in
 __vxlan_dev_create()

When a failure occurs in rtnl_configure_link(), the current code
calls unregister_netdevice() to roll back the earlier call to
register_netdevice(), and jumps to errout, which calls
vxlan_fdb_destroy().

However unregister_netdevice() calls transitively ndo_uninit(),
which is vxlan_uninit(), and that already takes care of deleting
the default FDB entry by calling vxlan_fdb_delete_default().
Since the entry added earlier in __vxlan_dev_create() is exactly
the default entry, the cleanup code in the errout block always
leads to double free and thus a panic.

Fix by skipping the rollback code and just returning.

Fixes: 0241b836732f ("vxlan: fix default fdb entry netlink notify ordering during netdev create")
Signed-off-by: Petr Machata <petrm@...lanox.com>
---
 drivers/net/vxlan.c | 15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

diff --git a/drivers/net/vxlan.c b/drivers/net/vxlan.c
index c9956c08edf5..139741617b90 100644
--- a/drivers/net/vxlan.c
+++ b/drivers/net/vxlan.c
@@ -3282,14 +3282,15 @@ static int __vxlan_dev_create(struct net *net, struct net_device *dev,
 	}
 
 	err = register_netdevice(dev);
-	if (err)
-		goto errout;
+	if (err) {
+		if (f)
+			vxlan_fdb_destroy(vxlan, f, false);
+		return err;
+	}
 
 	err = rtnl_configure_link(dev, NULL);
-	if (err) {
-		unregister_netdevice(dev);
+	if (err)
 		goto errout;
-	}
 
 	/* notify default fdb entry */
 	if (f)
@@ -3298,8 +3299,8 @@ static int __vxlan_dev_create(struct net *net, struct net_device *dev,
 	list_add(&vxlan->next, &vn->vxlan_list);
 	return 0;
 errout:
-	if (f)
-		vxlan_fdb_destroy(vxlan, f, false);
+	unregister_netdevice(dev);
+	/* the all_zeros_mac entry was deleted at vxlan_uninit */
 	return err;
 }
 
-- 
2.4.11