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From patchwork Mon Sep 18 16:28:57 2017
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Subject: [3/3] inet: fix improper empty comparison
X-Patchwork-Submitter: Josef Bacik <josef@toxicpanda.com>
X-Patchwork-Id: 815029
X-Patchwork-Delegate: davem@davemloft.net
Message-Id: <1505752137-15522-4-git-send-email-jbacik@fb.com>
To: davem@davemloft.net, netdev@vger.kernel.org,
 linux-kernel@vger.kernel.org, crobinso@redhat.com,
 labbott@redhat.com, kernel-team@fb.com
Cc: Josef Bacik <jbacik@fb.com>, stable@vger.kernel.org
Date: Mon, 18 Sep 2017 12:28:57 -0400
From: josef@toxicpanda.com
List-Id: <netdev.vger.kernel.org>

From: Josef Bacik <jbacik@fb.com>

When doing my reuseport rework I screwed up and changed a

if (hlist_empty(&tb->owners))

to

if (!hlist_empty(&tb->owners))

This is obviously bad as all of the reuseport/reuse logic was reversed,
which caused weird problems like allowing an ipv4 bind conflict if we
opened an ipv4 only socket on a port followed by an ipv6 only socket on
the same port.

Cc: stable@vger.kernel.org
Fixes: b9470c27607b ("inet: kill smallest_size and smallest_port")
Reported-by: Cole Robinson <crobinso@redhat.com>
Signed-off-by: Josef Bacik <jbacik@fb.com>
---
 net/ipv4/inet_connection_sock.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c
index a1bf30438bc5..c039c937ba90 100644
--- a/net/ipv4/inet_connection_sock.c
+++ b/net/ipv4/inet_connection_sock.c
@@ -321,7 +321,7 @@ int inet_csk_get_port(struct sock *sk, unsigned short snum)
 			goto fail_unlock;
 	}
 success:
-	if (!hlist_empty(&tb->owners)) {
+	if (hlist_empty(&tb->owners)) {
 		tb->fastreuse = reuse;
 		if (sk->sk_reuseport) {
 			tb->fastreuseport = FASTREUSEPORT_ANY;