From patchwork Mon May 24 15:25:41 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 447010 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=-19.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, 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 E327CC2B9F8 for ; Mon, 24 May 2021 15:41:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CAE8861934 for ; Mon, 24 May 2021 15:41:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234025AbhEXPmn (ORCPT ); Mon, 24 May 2021 11:42:43 -0400 Received: from mail.kernel.org ([198.145.29.99]:56576 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234055AbhEXPkh (ORCPT ); Mon, 24 May 2021 11:40:37 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 11B556143F; Mon, 24 May 2021 15:34:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1621870462; bh=11CFGkVqx0/wik8SpN3uohr7Pd+8jB70sbAWCEt25z8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=1vuxt8seZCrU+CYkKGp2xW2zuSIte3iliLPzDfBwuVmZstbn2/7pEcyFarGz25RHI ci0wpzFv790kp6+zscDaUKInX/SC/iDpYMuuwF1Iaw0+YvwuHKzGopxdbY25hiip2T Ad8M8uNljUENuzMLUqCD/KwJD6CDexb6s/VQA5yM= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, syzbot , Linus Torvalds , Tetsuo Handa Subject: [PATCH 4.14 37/37] tty: vt: always invoke vc->vc_sw->con_resize callback Date: Mon, 24 May 2021 17:25:41 +0200 Message-Id: <20210524152325.418859115@linuxfoundation.org> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210524152324.199089755@linuxfoundation.org> References: <20210524152324.199089755@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Tetsuo Handa commit ffb324e6f874121f7dce5bdae5e05d02baae7269 upstream. syzbot is reporting OOB write at vga16fb_imageblit() [1], for resize_screen() from ioctl(VT_RESIZE) returns 0 without checking whether requested rows/columns fit the amount of memory reserved for the graphical screen if current mode is KD_GRAPHICS. ---------- #include #include #include #include #include #include int main(int argc, char *argv[]) { const int fd = open("/dev/char/4:1", O_RDWR); struct vt_sizes vt = { 0x4100, 2 }; ioctl(fd, KDSETMODE, KD_GRAPHICS); ioctl(fd, VT_RESIZE, &vt); ioctl(fd, KDSETMODE, KD_TEXT); return 0; } ---------- Allow framebuffer drivers to return -EINVAL, by moving vc->vc_mode != KD_GRAPHICS check from resize_screen() to fbcon_resize(). Link: https://syzkaller.appspot.com/bug?extid=1f29e126cf461c4de3b3 [1] Reported-by: syzbot Suggested-by: Linus Torvalds Signed-off-by: Tetsuo Handa Tested-by: syzbot Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- drivers/tty/vt/vt.c | 2 +- drivers/video/fbdev/core/fbcon.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) --- a/drivers/tty/vt/vt.c +++ b/drivers/tty/vt/vt.c @@ -835,7 +835,7 @@ static inline int resize_screen(struct v /* Resizes the resolution of the display adapater */ int err = 0; - if (vc->vc_mode != KD_GRAPHICS && vc->vc_sw->con_resize) + if (vc->vc_sw->con_resize) err = vc->vc_sw->con_resize(vc, width, height, user); return err; --- a/drivers/video/fbdev/core/fbcon.c +++ b/drivers/video/fbdev/core/fbcon.c @@ -2003,7 +2003,7 @@ static int fbcon_resize(struct vc_data * return -EINVAL; DPRINTK("resize now %ix%i\n", var.xres, var.yres); - if (con_is_visible(vc)) { + if (con_is_visible(vc) && vc->vc_mode == KD_TEXT) { var.activate = FB_ACTIVATE_NOW | FB_ACTIVATE_FORCE; fb_set_var(info, &var);