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 906E5C6FA99 for ; Fri, 10 Mar 2023 14:43:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232876AbjCJOnK (ORCPT ); Fri, 10 Mar 2023 09:43:10 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60430 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232883AbjCJOmz (ORCPT ); Fri, 10 Mar 2023 09:42:55 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 39FBE120E80 for ; Fri, 10 Mar 2023 06:42:47 -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 dfw.source.kernel.org (Postfix) with ESMTPS id C86456195B for ; Fri, 10 Mar 2023 14:42:46 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id BB375C433EF; Fri, 10 Mar 2023 14:42:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1678459366; bh=nhI+dErhOR7W6KnBDPC6kIMB6vX+XedcG9dfbS8rOFc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=l+r8RTdhbOGSigLntz1P3PGLk5GnGHgB/dt+Zklg36MAe1s7/9m+vdp9i1bMgfuoy NjXFYQfA/X0HhDOymB146h/6WTltwgnfDxgO1YQVevgFuUWUSgy8ML1/ieahA79OKm tnsoVlF+ZHkScmAwkLvBHIBXwgQc6ytsxYOay2Q0= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Sven Schnelle , Jiri Slaby , Sasha Levin Subject: [PATCH 5.4 337/357] tty: fix out-of-bounds access in tty_driver_lookup_tty() Date: Fri, 10 Mar 2023 14:40:26 +0100 Message-Id: <20230310133749.529580027@linuxfoundation.org> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230310133733.973883071@linuxfoundation.org> References: <20230310133733.973883071@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@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 ddfe873b5fccb..37c46c65a65f4 100644 --- a/drivers/tty/tty_io.c +++ b/drivers/tty/tty_io.c @@ -1156,14 +1156,16 @@ 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