Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S933320AbbLGQRH (ORCPT <rfc822;w@1wt.eu>);
	Mon, 7 Dec 2015 11:17:07 -0500
Received: from mail.linuxfoundation.org ([140.211.169.12]:58855 "EHLO
	mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
	with ESMTP id S932844AbbLGO5Y (ORCPT
	<rfc822;linux-kernel@vger.kernel.org>);
	Mon, 7 Dec 2015 09:57:24 -0500
From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>, stable@vger.kernel.org,
        Renato Westphal <renatow@taghos.com.br>,
        "David S. Miller" <davem@davemloft.net>
Subject: [PATCH 4.2 003/124] tcp: remove improper preemption check in tcp_xmit_probe_skb()
Date: Mon,  7 Dec 2015 09:54:53 -0500
Message-Id: <20151207144919.853155174@linuxfoundation.org>
X-Mailer: git-send-email 2.6.3
In-Reply-To: <20151207144919.656035367@linuxfoundation.org>
References: <20151207144919.656035367@linuxfoundation.org>
User-Agent: quilt/0.64
MIME-Version: 1.0
Content-Type: text/plain; charset=ISO-8859-15
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org
Content-Length: 2614
Lines: 59

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

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

From: Renato Westphal <renatowestphal@gmail.com>

[ Upstream commit e2e8009ff72ad2a795b67785f3238af152146368 ]

Commit e520af48c7e5a introduced the following bug when setting the
TCP_REPAIR sockoption:

[ 2860.657036] BUG: using __this_cpu_add() in preemptible [00000000] code: daemon/12164
[ 2860.657045] caller is __this_cpu_preempt_check+0x13/0x20
[ 2860.657049] CPU: 1 PID: 12164 Comm: daemon Not tainted 4.2.3 #1
[ 2860.657051] Hardware name: Dell Inc. PowerEdge R210 II/0JP7TR, BIOS 2.0.5 03/13/2012
[ 2860.657054]  ffffffff81c7f071 ffff880231e9fdf8 ffffffff8185d765 0000000000000002
[ 2860.657058]  0000000000000001 ffff880231e9fe28 ffffffff8146ed91 ffff880231e9fe18
[ 2860.657062]  ffffffff81cd1a5d ffff88023534f200 ffff8800b9811000 ffff880231e9fe38
[ 2860.657065] Call Trace:
[ 2860.657072]  [<ffffffff8185d765>] dump_stack+0x4f/0x7b
[ 2860.657075]  [<ffffffff8146ed91>] check_preemption_disabled+0xe1/0xf0
[ 2860.657078]  [<ffffffff8146edd3>] __this_cpu_preempt_check+0x13/0x20
[ 2860.657082]  [<ffffffff817e0bc7>] tcp_xmit_probe_skb+0xc7/0x100
[ 2860.657085]  [<ffffffff817e1e2d>] tcp_send_window_probe+0x2d/0x30
[ 2860.657089]  [<ffffffff817d1d8c>] do_tcp_setsockopt.isra.29+0x74c/0x830
[ 2860.657093]  [<ffffffff817d1e9c>] tcp_setsockopt+0x2c/0x30
[ 2860.657097]  [<ffffffff81767b74>] sock_common_setsockopt+0x14/0x20
[ 2860.657100]  [<ffffffff817669e1>] SyS_setsockopt+0x71/0xc0
[ 2860.657104]  [<ffffffff81865172>] entry_SYSCALL_64_fastpath+0x16/0x75

Since tcp_xmit_probe_skb() can be called from process context, use
NET_INC_STATS() instead of NET_INC_STATS_BH().

Fixes: e520af48c7e5 ("tcp: add TCPWinProbe and TCPKeepAlive SNMP counters")
Signed-off-by: Renato Westphal <renatow@taghos.com.br>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 net/ipv4/tcp_output.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -3406,7 +3406,7 @@ static int tcp_xmit_probe_skb(struct soc
 	 */
 	tcp_init_nondata_skb(skb, tp->snd_una - !urgent, TCPHDR_ACK);
 	skb_mstamp_get(&skb->skb_mstamp);
-	NET_INC_STATS_BH(sock_net(sk), mib);
+	NET_INC_STATS(sock_net(sk), mib);
 	return tcp_transmit_skb(sk, skb, 0, GFP_ATOMIC);
 }
 


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