linux-kernel - [ 025/187] l2tp: fix a race in l2tp_ip

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: <20120712191524.586318194@linuxfoundation.org>
Date:	Thu, 12 Jul 2012 15:33:01 -0700
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:	Greg KH <gregkh@...uxfoundation.org>,
	torvalds@...ux-foundation.org, akpm@...ux-foundation.org,
	alan@...rguk.ukuu.org.uk, Eric Dumazet <edumazet@...gle.com>,
	James Chapman <jchapman@...alix.com>,
	Denys Fedoryshchenko <denys@...p.net.lb>,
	"David S. Miller" <davem@...emloft.net>
Subject: [ 025/187] l2tp: fix a race in l2tp_ip_sendmsg()

From: Greg KH <gregkh@...uxfoundation.org>

3.4-stable review patch.  If anyone has any objections, please let me know.

------------------


From: Eric Dumazet <edumazet@...gle.com>

[ Upstream commit 4399a4df98a63e30fd16e9d0cecc46ea92269e8f ]

Commit 081b1b1bb27f (l2tp: fix l2tp_ip_sendmsg() route handling) added
a race, in case IP route cache is disabled.

In this case, we should not do the dst_release(&rt->dst), since it'll
free the dst immediately, instead of waiting a RCU grace period.

Signed-off-by: Eric Dumazet <edumazet@...gle.com>
Cc: James Chapman <jchapman@...alix.com>
Cc: Denys Fedoryshchenko <denys@...p.net.lb>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 net/l2tp/l2tp_ip.c |    9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

--- a/net/l2tp/l2tp_ip.c
+++ b/net/l2tp/l2tp_ip.c
@@ -516,10 +516,12 @@ static int l2tp_ip_sendmsg(struct kiocb
 					   sk->sk_bound_dev_if);
 		if (IS_ERR(rt))
 			goto no_route;
-		if (connected)
+		if (connected) {
 			sk_setup_caps(sk, &rt->dst);
-		else
-			dst_release(&rt->dst); /* safe since we hold rcu_read_lock */
+		} else {
+			skb_dst_set(skb, &rt->dst);
+			goto xmit;
+		}
 	}
 
 	/* We dont need to clone dst here, it is guaranteed to not disappear.
@@ -527,6 +529,7 @@ static int l2tp_ip_sendmsg(struct kiocb
 	 */
 	skb_dst_set_noref(skb, &rt->dst);
 
+xmit:
 	/* Queue the packet to IP for output */
 	rc = ip_queue_xmit(skb, &inet->cork.fl);
 	rcu_read_unlock();


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/