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 X-Spam-Level: X-Spam-Status: No, score=-18.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2344DC64E75 for ; Mon, 23 Nov 2020 13:26:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B7EC02080A for ; Mon, 23 Nov 2020 13:26:49 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="u8FwKPgU" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731974AbgKWN0f (ORCPT ); Mon, 23 Nov 2020 08:26:35 -0500 Received: from mail.kernel.org ([198.145.29.99]:43808 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731082AbgKWMc2 (ORCPT ); Mon, 23 Nov 2020 07:32:28 -0500 Received: from localhost (83-86-74-64.cable.dynamic.v4.ziggo.nl [83.86.74.64]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id A508520728; Mon, 23 Nov 2020 12:32:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1606134747; bh=E1LT5lMp5sUTENxUoH2r6Gvo/RNc/kwo1PUsUpVQOnk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=u8FwKPgUcereFsreDgJ7UFKRKMQJBzaaYA100kcE2wS8ivTZic2HNblh0Lw+GPUIQ Q4VA1/NTg5U4F4Sj6XJIu67YLed4y5BXnBXN0Eo9TdLJ1vUmxKxXUCz56jLnUleC4w 0XjQJ9vJNvqzxSUPaf/Mk5dUFyZa/wXOXUSFu3NM= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, =?UTF-8?q?=E7=A7=A6=E4=B8=96=E6=9D=BE?= , Samuel Thibault Subject: [PATCH 4.19 66/91] speakup: Do not let the line discipline be used several times Date: Mon, 23 Nov 2020 13:22:26 +0100 Message-Id: <20201123121812.529516001@linuxfoundation.org> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20201123121809.285416732@linuxfoundation.org> References: <20201123121809.285416732@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: Samuel Thibault commit d4122754442799187d5d537a9c039a49a67e57f1 upstream. Speakup has only one speakup_tty variable to store the tty it is managing. This makes sense since its codebase currently assumes that there is only one user who controls the screen reading. That however means that we have to forbid using the line discipline several times, otherwise the second closure would try to free a NULL ldisc_data, leading to general protection fault: 0000 [#1] SMP KASAN PTI RIP: 0010:spk_ttyio_ldisc_close+0x2c/0x60 Call Trace: tty_ldisc_release+0xa2/0x340 tty_release_struct+0x17/0xd0 tty_release+0x9d9/0xcc0 __fput+0x231/0x740 task_work_run+0x12c/0x1a0 do_exit+0x9b5/0x2230 ? release_task+0x1240/0x1240 ? __do_page_fault+0x562/0xa30 do_group_exit+0xd5/0x2a0 __x64_sys_exit_group+0x35/0x40 do_syscall_64+0x89/0x2b0 ? page_fault+0x8/0x30 entry_SYSCALL_64_after_hwframe+0x44/0xa9 Cc: stable@vger.kernel.org Reported-by: 秦世松 Signed-off-by: Samuel Thibault Tested-by: Shisong Qin Link: https://lore.kernel.org/r/20201110183541.fzgnlwhjpgqzjeth@function Signed-off-by: Greg Kroah-Hartman --- drivers/staging/speakup/spk_ttyio.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-) --- a/drivers/staging/speakup/spk_ttyio.c +++ b/drivers/staging/speakup/spk_ttyio.c @@ -49,15 +49,25 @@ static int spk_ttyio_ldisc_open(struct t if (tty->ops->write == NULL) return -EOPNOTSUPP; + + mutex_lock(&speakup_tty_mutex); + if (speakup_tty) { + mutex_unlock(&speakup_tty_mutex); + return -EBUSY; + } speakup_tty = tty; ldisc_data = kmalloc(sizeof(struct spk_ldisc_data), GFP_KERNEL); - if (!ldisc_data) + if (!ldisc_data) { + speakup_tty = NULL; + mutex_unlock(&speakup_tty_mutex); return -ENOMEM; + } sema_init(&ldisc_data->sem, 0); ldisc_data->buf_free = true; speakup_tty->disc_data = ldisc_data; + mutex_unlock(&speakup_tty_mutex); return 0; }