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 4CFC3C678D5 for ; Fri, 3 Mar 2023 22:54:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232311AbjCCWyQ (ORCPT ); Fri, 3 Mar 2023 17:54:16 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46440 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231838AbjCCWyK (ORCPT ); Fri, 3 Mar 2023 17:54:10 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 320EC21965; Fri, 3 Mar 2023 14:53:43 -0800 (PST) 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 D8BEBB81A38; Fri, 3 Mar 2023 21:48:59 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id BA446C4339C; Fri, 3 Mar 2023 21:48:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1677880139; bh=iLssFjCE/ZuSk8mC8YKfS8WArw1eZk+D/bVI0cb4e7k=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ksC2lUyygJfSiFTrLPDALiGz4fnT4s12ryXmGhZZz0a6lDJM4lMLu1X9q7q35FZEt zU0XeFHSMN3sTZCGa+CVTDrnwRtY/zKb8RJkXDAjL/4fE+Hli8gP93FXPMNizjeOMh RKnGKHSxX8o7VNbMCwr92ETOQS095djfK9bCJfSQ2LEd91uzXCkOgZA2QqPS8FITud AV3bEy6S+1LK4/eRYf36m/rqmeHUnuzpa6tWUFcQfxBjimcXsYRADTPj6gO7clLa1E /fojL8fifcWHu4O+tImmEsusMtF0O6w88PLjH3eT72u0CMJt+foi5n15HY2o9ibeeY K8qBbmTR+EDeg== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Sven Schnelle , Jiri Slaby , Greg Kroah-Hartman , Sasha Levin Subject: [PATCH AUTOSEL 4.19 05/16] tty: fix out-of-bounds access in tty_driver_lookup_tty() Date: Fri, 3 Mar 2023 16:48:38 -0500 Message-Id: <20230303214849.1454002-5-sashal@kernel.org> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230303214849.1454002-1-sashal@kernel.org> References: <20230303214849.1454002-1-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: Sven Schnelle [ Upstream commit db4df8e9d79e7d37732c1a1b560958e8dadfefa1 ] When specifying an invalid console= device like console=tty3270, tty_driver_lookup_tty() returns the tty struct without checking whether index is a valid number. To reproduce: qemu-system-x86_64 -enable-kvm -nographic -serial mon:stdio \ -kernel ../linux-build-x86/arch/x86/boot/bzImage \ -append "console=ttyS0 console=tty3270" This crashes with: [ 0.770599] BUG: kernel NULL pointer dereference, address: 00000000000000ef [ 0.771265] #PF: supervisor read access in kernel mode [ 0.771773] #PF: error_code(0x0000) - not-present page [ 0.772609] Oops: 0000 [#1] PREEMPT SMP PTI [ 0.774878] RIP: 0010:tty_open+0x268/0x6f0 [ 0.784013] chrdev_open+0xbd/0x230 [ 0.784444] ? cdev_device_add+0x80/0x80 [ 0.784920] do_dentry_open+0x1e0/0x410 [ 0.785389] path_openat+0xca9/0x1050 [ 0.785813] do_filp_open+0xaa/0x150 [ 0.786240] file_open_name+0x133/0x1b0 [ 0.786746] filp_open+0x27/0x50 [ 0.787244] console_on_rootfs+0x14/0x4d [ 0.787800] kernel_init_freeable+0x1e4/0x20d [ 0.788383] ? rest_init+0xc0/0xc0 [ 0.788881] kernel_init+0x11/0x120 [ 0.789356] ret_from_fork+0x22/0x30 Signed-off-by: Sven Schnelle Reviewed-by: Jiri Slaby Link: https://lore.kernel.org/r/20221209112737.3222509-2-svens@linux.ibm.com Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin --- drivers/tty/tty_io.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c index b6f42d0ee6269..d3e6b66155536 100644 --- a/drivers/tty/tty_io.c +++ b/drivers/tty/tty_io.c @@ -1155,14 +1155,16 @@ static struct tty_struct *tty_driver_lookup_tty(struct tty_driver *driver, { struct tty_struct *tty; - if (driver->ops->lookup) + if (driver->ops->lookup) { if (!file) tty = ERR_PTR(-EIO); else tty = driver->ops->lookup(driver, file, idx); - else + } else { + if (idx >= driver->num) + return ERR_PTR(-EINVAL); tty = driver->ttys[idx]; - + } if (!IS_ERR(tty)) tty_kref_get(tty); return tty; -- 2.39.2