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 C1142C46467 for ; Mon, 18 Apr 2022 13:21:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S243222AbiDRNXx (ORCPT ); Mon, 18 Apr 2022 09:23:53 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41038 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241550AbiDRNDK (ORCPT ); Mon, 18 Apr 2022 09:03:10 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D8CDD33A0F; Mon, 18 Apr 2022 05:43:41 -0700 (PDT) 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 ams.source.kernel.org (Postfix) with ESMTPS id 82393B80E4B; Mon, 18 Apr 2022 12:43:40 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id C08B2C385A1; Mon, 18 Apr 2022 12:43:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1650285819; bh=bLcI8hbjt28iQGSQ6pHqoLkLd+ORRcK4bONCyvx1t0I=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ph3hKcSqfygvNawm7KogcSqad45+gZ+uraca4LpLHR7LFkq3JwDKwsmM38ViO7nph GlRDcpjegdsImQ8U8dyDbmMPn8kUz3K72yaABi8jLAq9AGsOoiatI+/xrFsn6rooHM VnAZngYGgmVDnmVrItpszslsEcyuav9bXtVYYfGc= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Duoming Zhou , Jiri Slaby , Jakub Kicinski , Sasha Levin Subject: [PATCH 5.4 35/63] drivers: net: slip: fix NPD bug in sl_tx_timeout() Date: Mon, 18 Apr 2022 14:13:32 +0200 Message-Id: <20220418121136.595236205@linuxfoundation.org> X-Mailer: git-send-email 2.35.3 In-Reply-To: <20220418121134.149115109@linuxfoundation.org> References: <20220418121134.149115109@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Duoming Zhou [ Upstream commit ec4eb8a86ade4d22633e1da2a7d85a846b7d1798 ] When a slip driver is detaching, the slip_close() will act to cleanup necessary resources and sl->tty is set to NULL in slip_close(). Meanwhile, the packet we transmit is blocked, sl_tx_timeout() will be called. Although slip_close() and sl_tx_timeout() use sl->lock to synchronize, we don`t judge whether sl->tty equals to NULL in sl_tx_timeout() and the null pointer dereference bug will happen. (Thread 1) | (Thread 2) | slip_close() | spin_lock_bh(&sl->lock) | ... ... | sl->tty = NULL //(1) sl_tx_timeout() | spin_unlock_bh(&sl->lock) spin_lock(&sl->lock); | ... | ... tty_chars_in_buffer(sl->tty)| if (tty->ops->..) //(2) | ... | synchronize_rcu() We set NULL to sl->tty in position (1) and dereference sl->tty in position (2). This patch adds check in sl_tx_timeout(). If sl->tty equals to NULL, sl_tx_timeout() will goto out. Signed-off-by: Duoming Zhou Reviewed-by: Jiri Slaby Link: https://lore.kernel.org/r/20220405132206.55291-1-duoming@zju.edu.cn Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- drivers/net/slip/slip.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/net/slip/slip.c b/drivers/net/slip/slip.c index 8e56a41dd758..096617982998 100644 --- a/drivers/net/slip/slip.c +++ b/drivers/net/slip/slip.c @@ -471,7 +471,7 @@ static void sl_tx_timeout(struct net_device *dev) spin_lock(&sl->lock); if (netif_queue_stopped(dev)) { - if (!netif_running(dev)) + if (!netif_running(dev) || !sl->tty) goto out; /* May be we must check transmitter timeout here ? -- 2.35.1