netdev - [patch] packet: missing dev_put() in packet_do

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>] [day] [month] [year] [list]

Date:	Tue, 28 Jul 2015 01:32:21 +0300
From:	Dan Carpenter <dan.carpenter@...cle.com>
To:	"David S. Miller" <davem@...emloft.net>
Cc:	Willem de Bruijn <willemb@...gle.com>,
	Eric Dumazet <edumazet@...gle.com>,
	Daniel Borkmann <dborkman@...hat.com>,
	Alexander Drozdov <al.drozdov@...il.com>,
	Eyal Birger <eyal.birger@...il.com>,
	"Michael S. Tsirkin" <mst@...hat.com>, netdev@...r.kernel.org,
	Lars Westerhoff <lars.westerhoff@...tec.eu>,
	Boris Nikolaus <boris.nikolaus@...tec.eu>,
	krystian.garbaciak@...tec.eu,
	Michael Eyrich <michael.eyrich@...tec.eu>, security@...nel.org
Subject: [patch] packet: missing dev_put() in packet_do_bind()

From: Lars Westerhoff <lars.westerhoff@...tec.eu>

When binding a PF_PACKET socket, the use count of the bound interface is
always increased with dev_hold in dev_get_by_{index,name}.  However,
when rebound with the same protocol and device as in the previous bind
the use count of the interface was not decreased.  Ultimately, this
caused the deletion of the interface to fail with the following message:

unregister_netdevice: waiting for dummy0 to become free. Usage count = 1

This patch moves the dev_put out of the conditional part that was only
executed when either the protocol or device changed on a bind.

Fixes: 902fefb82ef7 ('packet: improve socket create/bind latency in some cases')
Signed-off-by: Lars Westerhoff <lars.westerhoff@...tec.eu>
Signed-off-by: Dan Carpenter <dan.carpenter@...cle.com>
Reviewed-by: Daniel Borkmann <dborkman@...hat.com>

diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index c9e8741..c7c42eb 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -2784,7 +2784,7 @@ static int packet_release(struct socket *sock)
 static int packet_do_bind(struct sock *sk, struct net_device *dev, __be16 proto)
 {
 	struct packet_sock *po = pkt_sk(sk);
-	const struct net_device *dev_curr;
+	struct net_device *dev_curr;
 	__be16 proto_curr;
 	bool need_rehook;
 
@@ -2808,15 +2808,13 @@ static int packet_do_bind(struct sock *sk, struct net_device *dev, __be16 proto)
 
 		po->num = proto;
 		po->prot_hook.type = proto;
-
-		if (po->prot_hook.dev)
-			dev_put(po->prot_hook.dev);
-
 		po->prot_hook.dev = dev;
 
 		po->ifindex = dev ? dev->ifindex : 0;
 		packet_cached_dev_assign(po, dev);
 	}
+	if (dev_curr)
+		dev_put(dev_curr);
 
 	if (proto == 0 || !need_rehook)
 		goto out_unlock;
--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html