From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4FEF5C433F5 for ; Mon, 27 Dec 2021 19:07:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233665AbhL0THz (ORCPT ); Mon, 27 Dec 2021 14:07:55 -0500 Received: from sin.source.kernel.org ([145.40.73.55]:49718 "EHLO sin.source.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233232AbhL0TGz (ORCPT ); Mon, 27 Dec 2021 14:06:55 -0500 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by sin.source.kernel.org (Postfix) with ESMTPS id 6A19BCE114B; Mon, 27 Dec 2021 19:06:52 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id BCCC6C36AEE; Mon, 27 Dec 2021 19:06:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1640632010; bh=055HlUvUQ2TxKb4Z4cpIUxi7M++pUMXyhB1W32PSMEI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=i5aDzhN2vpuie1Sq8m1Ky624ZP2lRHIZXJdrUIvRL+CnlN2IjTGmhYcvo0jV5ec56 lajKuZ2i8IpZdPs9HIG27TNQ2hPUZuRlwjHM8onUmQBl6vDUtvNlvYAlW/w50+7Dce Homz+eSFRYv+SKUMVQuAMhmeP6bpFmj7Mqr6Rq/8hAXoljAFNPlnydggKImSS51vc8 sUGNbAiTgj1KwJ1BPRYRhOJDkqC1bfJgjK6gcymQb1NAJR9OlGjygR7C2mfvK92QPg rcFnWSFWvaRuAND4DRoT5is/4Y9RT7qYqfjutyIcAwzRfzMO8qX13B+hM8MCbkeNNn +RWg2Dx5TtgIg== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Lin Ma , Hanjie Wu , "David S . Miller" , Sasha Levin , jreuter@yaina.de, kuba@kernel.org, linux-hams@vger.kernel.org, netdev@vger.kernel.org Subject: [PATCH AUTOSEL 4.9 2/4] ax25: NPD bug when detaching AX25 device Date: Mon, 27 Dec 2021 14:06:44 -0500 Message-Id: <20211227190647.1043514-2-sashal@kernel.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20211227190647.1043514-1-sashal@kernel.org> References: <20211227190647.1043514-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Lin Ma [ Upstream commit 1ade48d0c27d5da1ccf4b583d8c5fc8b534a3ac8 ] The existing cleanup routine implementation is not well synchronized with the syscall routine. When a device is detaching, below race could occur. static int ax25_sendmsg(...) { ... lock_sock() ax25 = sk_to_ax25(sk); if (ax25->ax25_dev == NULL) // CHECK ... ax25_queue_xmit(skb, ax25->ax25_dev->dev); // USE ... } static void ax25_kill_by_device(...) { ... if (s->ax25_dev == ax25_dev) { s->ax25_dev = NULL; ... } Other syscall functions like ax25_getsockopt, ax25_getname, ax25_info_show also suffer from similar races. To fix them, this patch introduce lock_sock() into ax25_kill_by_device in order to guarantee that the nullify action in cleanup routine cannot proceed when another socket request is pending. Signed-off-by: Hanjie Wu Signed-off-by: Lin Ma Signed-off-by: David S. Miller Signed-off-by: Sasha Levin --- net/ax25/af_ax25.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/net/ax25/af_ax25.c b/net/ax25/af_ax25.c index 64fede18aa33f..f4c8567e91b38 100644 --- a/net/ax25/af_ax25.c +++ b/net/ax25/af_ax25.c @@ -88,8 +88,10 @@ static void ax25_kill_by_device(struct net_device *dev) again: ax25_for_each(s, &ax25_list) { if (s->ax25_dev == ax25_dev) { - s->ax25_dev = NULL; spin_unlock_bh(&ax25_list_lock); + lock_sock(s->sk); + s->ax25_dev = NULL; + release_sock(s->sk); ax25_disconnect(s, ENETUNREACH); spin_lock_bh(&ax25_list_lock); -- 2.34.1