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=-18.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS 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 B4214C636C9 for ; Wed, 21 Jul 2021 10:58:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 91AA56120F for ; Wed, 21 Jul 2021 10:58:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235424AbhGUKQ4 (ORCPT ); Wed, 21 Jul 2021 06:16:56 -0400 Received: from mail.kernel.org ([198.145.29.99]:57638 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239002AbhGUKBn (ORCPT ); Wed, 21 Jul 2021 06:01:43 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id EB80961009; Wed, 21 Jul 2021 10:42:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1626864128; bh=f51bf7ScK9jN7XnyGwgVdlPyyuIzZuzZJOxILPTPQY0=; h=Subject:To:From:Date:From; b=K2dBoHLrY+0Qq/wh6qUkPbNm+eDhkGdypv9i+8vfdLqc38OINulGipcAq/J41WESj 7DL8qWicZQoZNTBLnC4OR+5xt0Z0ZYEEaVJRIfZt1yfg+ppl1fWeeBrm6KaW4YatNG Iwc2kgmRty4OGwaDfP8pr1GWuCQdz9dU4hPdjx2Y= Subject: patch "tty: Fix out-of-bound vmalloc access in imageblit" added to tty-testing To: igormtorrente@gmail.com, gregkh@linuxfoundation.org, stable@vger.kernel.org From: Date: Wed, 21 Jul 2021 12:41:58 +0200 Message-ID: <1626864118165226@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org This is a note to let you know that I've just added the patch titled tty: Fix out-of-bound vmalloc access in imageblit to my tty git tree which can be found at git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty.git in the tty-testing branch. The patch will show up in the next release of the linux-next tree (usually sometime within the next 24 hours during the week.) The patch will be merged to the tty-next branch sometime soon, after it passes testing, and the merge window is open. If you have any questions about this process, please let me know. >From 3b0c406124719b625b1aba431659f5cdc24a982c Mon Sep 17 00:00:00 2001 From: Igor Matheus Andrade Torrente Date: Mon, 28 Jun 2021 10:45:09 -0300 Subject: tty: Fix out-of-bound vmalloc access in imageblit This issue happens when a userspace program does an ioctl FBIOPUT_VSCREENINFO passing the fb_var_screeninfo struct containing only the fields xres, yres, and bits_per_pixel with values. If this struct is the same as the previous ioctl, the vc_resize() detects it and doesn't call the resize_screen(), leaving the fb_var_screeninfo incomplete. And this leads to the updatescrollmode() calculates a wrong value to fbcon_display->vrows, which makes the real_y() return a wrong value of y, and that value, eventually, causes the imageblit to access an out-of-bound address value. To solve this issue I made the resize_screen() be called even if the screen does not need any resizing, so it will "fix and fill" the fb_var_screeninfo independently. Cc: stable # after 5.15-rc2 is out, give it time to bake Reported-and-tested-by: syzbot+858dc7a2f7ef07c2c219@syzkaller.appspotmail.com Signed-off-by: Igor Matheus Andrade Torrente Link: https://lore.kernel.org/r/20210628134509.15895-1-igormtorrente@gmail.com Signed-off-by: Greg Kroah-Hartman --- drivers/tty/vt/vt.c | 21 +++++++++++++++++++-- 1 file changed, 19 insertions(+), 2 deletions(-) diff --git a/drivers/tty/vt/vt.c b/drivers/tty/vt/vt.c index ef981d3b7bb4..484eda1958f5 100644 --- a/drivers/tty/vt/vt.c +++ b/drivers/tty/vt/vt.c @@ -1219,8 +1219,25 @@ static int vc_do_resize(struct tty_struct *tty, struct vc_data *vc, new_row_size = new_cols << 1; new_screen_size = new_row_size * new_rows; - if (new_cols == vc->vc_cols && new_rows == vc->vc_rows) - return 0; + if (new_cols == vc->vc_cols && new_rows == vc->vc_rows) { + /* + * This function is being called here to cover the case + * where the userspace calls the FBIOPUT_VSCREENINFO twice, + * passing the same fb_var_screeninfo containing the fields + * yres/xres equal to a number non-multiple of vc_font.height + * and yres_virtual/xres_virtual equal to number lesser than the + * vc_font.height and yres/xres. + * In the second call, the struct fb_var_screeninfo isn't + * being modified by the underlying driver because of the + * if above, and this causes the fbcon_display->vrows to become + * negative and it eventually leads to out-of-bound + * access by the imageblit function. + * To give the correct values to the struct and to not have + * to deal with possible errors from the code below, we call + * the resize_screen here as well. + */ + return resize_screen(vc, new_cols, new_rows, user); + } if (new_screen_size > KMALLOC_MAX_SIZE || !new_screen_size) return -EINVAL; -- 2.32.0