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=-4.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED 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 9B009C43610 for ; Sun, 11 Nov 2018 20:00:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 682C1214E0 for ; Sun, 11 Nov 2018 20:00:08 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 682C1214E0 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=decadent.org.uk Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730978AbeKLFte (ORCPT ); Mon, 12 Nov 2018 00:49:34 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:51302 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730690AbeKLFse (ORCPT ); Mon, 12 Nov 2018 00:48:34 -0500 Received: from [192.168.4.242] (helo=deadeye) by shadbolt.decadent.org.uk with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.89) (envelope-from ) id 1gLvsv-0000oO-5i; Sun, 11 Nov 2018 19:59:05 +0000 Received: from ben by deadeye with local (Exim 4.91) (envelope-from ) id 1gLvsV-0001el-08; Sun, 11 Nov 2018 19:58:39 +0000 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, syzbot+17a8efdf800000@syzkaller.appspotmail.com, "Alexander Potapenko" , "Greg Kroah-Hartman" Date: Sun, 11 Nov 2018 19:49:05 +0000 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.16 213/366] vt: prevent leaking uninitialized data to userspace via /dev/vcs* In-Reply-To: X-SA-Exim-Connect-IP: 192.168.4.242 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.61-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Alexander Potapenko commit 21eff69aaaa0e766ca0ce445b477698dc6a9f55a upstream. KMSAN reported an infoleak when reading from /dev/vcs*: BUG: KMSAN: kernel-infoleak in vcs_read+0x18ba/0x1cc0 Call Trace: ... kmsan_copy_to_user+0x7a/0x160 mm/kmsan/kmsan.c:1253 copy_to_user ./include/linux/uaccess.h:184 vcs_read+0x18ba/0x1cc0 drivers/tty/vt/vc_screen.c:352 __vfs_read+0x1b2/0x9d0 fs/read_write.c:416 vfs_read+0x36c/0x6b0 fs/read_write.c:452 ... Uninit was created at: kmsan_save_stack_with_flags mm/kmsan/kmsan.c:279 kmsan_internal_poison_shadow+0xb8/0x1b0 mm/kmsan/kmsan.c:189 kmsan_kmalloc+0x94/0x100 mm/kmsan/kmsan.c:315 __kmalloc+0x13a/0x350 mm/slub.c:3818 kmalloc ./include/linux/slab.h:517 vc_allocate+0x438/0x800 drivers/tty/vt/vt.c:787 con_install+0x8c/0x640 drivers/tty/vt/vt.c:2880 tty_driver_install_tty drivers/tty/tty_io.c:1224 tty_init_dev+0x1b5/0x1020 drivers/tty/tty_io.c:1324 tty_open_by_driver drivers/tty/tty_io.c:1959 tty_open+0x17b4/0x2ed0 drivers/tty/tty_io.c:2007 chrdev_open+0xc25/0xd90 fs/char_dev.c:417 do_dentry_open+0xccc/0x1440 fs/open.c:794 vfs_open+0x1b6/0x2f0 fs/open.c:908 ... Bytes 0-79 of 240 are uninitialized Consistently allocating |vc_screenbuf| with kzalloc() fixes the problem Reported-by: syzbot+17a8efdf800000@syzkaller.appspotmail.com Signed-off-by: Alexander Potapenko Signed-off-by: Greg Kroah-Hartman Signed-off-by: Ben Hutchings --- drivers/tty/vt/vt.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- a/drivers/tty/vt/vt.c +++ b/drivers/tty/vt/vt.c @@ -782,7 +782,7 @@ int vc_allocate(unsigned int currcons) / if (!*vc->vc_uni_pagedir_loc) con_set_default_unimap(vc); - vc->vc_screenbuf = kmalloc(vc->vc_screenbuf_size, GFP_KERNEL); + vc->vc_screenbuf = kzalloc(vc->vc_screenbuf_size, GFP_KERNEL); if (!vc->vc_screenbuf) goto err_free; @@ -869,7 +869,7 @@ static int vc_do_resize(struct tty_struc if (new_screen_size > (4 << 20)) return -EINVAL; - newscreen = kmalloc(new_screen_size, GFP_USER); + newscreen = kzalloc(new_screen_size, GFP_USER); if (!newscreen) return -ENOMEM;