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 DC78CC433F5 for ; Tue, 12 Apr 2022 01:05:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S245687AbiDLBHW (ORCPT ); Mon, 11 Apr 2022 21:07:22 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34292 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1345847AbiDLA6l (ORCPT ); Mon, 11 Apr 2022 20:58:41 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CC24333EB4; Mon, 11 Apr 2022 17:51:46 -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 F3FFFB81996; Tue, 12 Apr 2022 00:51:44 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4DC90C385A9; Tue, 12 Apr 2022 00:51:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1649724703; bh=bLcI8hbjt28iQGSQ6pHqoLkLd+ORRcK4bONCyvx1t0I=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Rw9fWxRpqLgNAimyMmyaX7bp/J6CIhUWqcGblQXq2Gy1p2jOj1G1XpBqNgsJLjP+f LzllDjhvjtXRwhWZBsrr30ubhXilEz8p2+AQ0CdkdHt1ldCKAjUc2tccMtyrsW+fbj dU++mv7gR1g4w67L+Ey29s1iKagQbYrq4LRsD5iVg4JD0NwEvGBxHNhSMrgoeDCg47 3h1u5ahUhU07yaA6D8YeDa5KxLcARTo6+2D44qhLmuBJMc1hw++VpTVz9YIJ0PwuCh NiTUtSy7JE7HMacTTCiygPi8ZCYyAjHGvK+ZN//8MUzVNDKMVIhaJJKUcLZlVqz0Wn S+HejBAWRLtQA== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Duoming Zhou , Jiri Slaby , Jakub Kicinski , Sasha Levin , davem@davemloft.net, pabeni@redhat.com, gregkh@linuxfoundation.org, mkl@pengutronix.de, dmitry.torokhov@gmail.com, bigeasy@linutronix.de, arnd@arndb.de, netdev@vger.kernel.org Subject: [PATCH AUTOSEL 5.4 20/21] drivers: net: slip: fix NPD bug in sl_tx_timeout() Date: Mon, 11 Apr 2022 20:50:39 -0400 Message-Id: <20220412005042.351105-20-sashal@kernel.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220412005042.351105-1-sashal@kernel.org> References: <20220412005042.351105-1-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: 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