From patchwork Wed Apr 1 16:18:47 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 228386 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=-6.8 required=3.0 tests=DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham 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 9E157C43331 for ; Wed, 1 Apr 2020 16:46:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 752E320BED for ; Wed, 1 Apr 2020 16:46:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1585759612; bh=9/GVYEdPPBR2AV0UCFVKcd7QD1qTeXd0Zbj4nmO0Pls=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=Sbo2qo2lcf+We4BCn6cWd3e3pWgeuUPnXYfTfDd/Utf68T2eLRNnY31HxoUCeqGRK wbLmz9iKCu5RQxI1bTM75cPde0bqhlOLJf1lJIKWYtsDtSn0EkHO37YdEEQELNgQii 8AxLjoiIpRbo58NGX3M+jF5mQ5DE1WOchOgfvO14= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389819AbgDAQqv (ORCPT ); Wed, 1 Apr 2020 12:46:51 -0400 Received: from mail.kernel.org ([198.145.29.99]:48390 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2389993AbgDAQqv (ORCPT ); Wed, 1 Apr 2020 12:46:51 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (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 DE44620784; Wed, 1 Apr 2020 16:46:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1585759610; bh=9/GVYEdPPBR2AV0UCFVKcd7QD1qTeXd0Zbj4nmO0Pls=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=rIKVgK74JXblWiN+wYo7wNNS+ZkACleesRvtZXEm28Uvs8LIOEpT+48dkia6+YjNn ARP11naS9XhVnM50UDjKPSeM95JN6kak55Gkk52tMqlLhfxWjhBjxzUxY1iSp4CwpU 2WJJEZLoAb08RHDZhyOWLaRxMYwXYdMGoU5LHvzo= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Eric Biggers Subject: [PATCH 4.14 135/148] vt: vt_ioctl: remove unnecessary console allocation checks Date: Wed, 1 Apr 2020 18:18:47 +0200 Message-Id: <20200401161605.247003463@linuxfoundation.org> X-Mailer: git-send-email 2.26.0 In-Reply-To: <20200401161552.245876366@linuxfoundation.org> References: <20200401161552.245876366@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Eric Biggers commit 1aa6e058dd6cd04471b1f21298270014daf48ac9 upstream. The vc_cons_allocated() checks in vt_ioctl() and vt_compat_ioctl() are unnecessary because they can only be reached by calling ioctl() on an open tty, which implies the corresponding virtual console is allocated. And even if the virtual console *could* be freed concurrently, then these checks would be broken since they aren't done under console_lock, and the vc_data is dereferenced before them anyway. So, remove these unneeded checks to avoid confusion. Signed-off-by: Eric Biggers Link: https://lore.kernel.org/r/20200224080326.295046-1-ebiggers@kernel.org Signed-off-by: Greg Kroah-Hartman --- drivers/tty/vt/vt_ioctl.c | 21 ++------------------- 1 file changed, 2 insertions(+), 19 deletions(-) --- a/drivers/tty/vt/vt_ioctl.c +++ b/drivers/tty/vt/vt_ioctl.c @@ -350,22 +350,13 @@ int vt_ioctl(struct tty_struct *tty, { struct vc_data *vc = tty->driver_data; struct console_font_op op; /* used in multiple places here */ - unsigned int console; + unsigned int console = vc->vc_num; unsigned char ucval; unsigned int uival; void __user *up = (void __user *)arg; int i, perm; int ret = 0; - console = vc->vc_num; - - - if (!vc_cons_allocated(console)) { /* impossible? */ - ret = -ENOIOCTLCMD; - goto out; - } - - /* * To have permissions to do most of the vt ioctls, we either have * to be the owner of the tty, or have CAP_SYS_TTY_CONFIG. @@ -1195,18 +1186,10 @@ long vt_compat_ioctl(struct tty_struct * { struct vc_data *vc = tty->driver_data; struct console_font_op op; /* used in multiple places here */ - unsigned int console; void __user *up = (void __user *)arg; int perm; int ret = 0; - console = vc->vc_num; - - if (!vc_cons_allocated(console)) { /* impossible? */ - ret = -ENOIOCTLCMD; - goto out; - } - /* * To have permissions to do most of the vt ioctls, we either have * to be the owner of the tty, or have CAP_SYS_TTY_CONFIG. @@ -1266,7 +1249,7 @@ long vt_compat_ioctl(struct tty_struct * arg = (unsigned long)compat_ptr(arg); goto fallback; } -out: + return ret; fallback: