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=-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=unavailable 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 ED29EC2B9F8 for ; Mon, 24 May 2021 15:38:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C248761601 for ; Mon, 24 May 2021 15:38:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234249AbhEXPjO (ORCPT ); Mon, 24 May 2021 11:39:14 -0400 Received: from mail.kernel.org ([198.145.29.99]:50504 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233889AbhEXPgX (ORCPT ); Mon, 24 May 2021 11:36:23 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 6FA916140E; Mon, 24 May 2021 15:32:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1621870359; bh=SsbNvQaUdj20wLzoljS0f2x1A3hb77seJHzsZL169dQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=sG2hVx1IJLFkWk/lK0WBMsn1nszMcZwqeFkxpRl5Cq8bDSs+/yrcKui0EDdQQZd3E R3fyOQ0H68AWfAGSWf6X8jVUJwXG6ygwQmdrIIlXusGlddWoiEKxENZFLwFMmGevrb LEJdfb+lIgyA9Nv57Iwg2dN+aoQXblX19p8BJDKM= 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 4.9 35/36] tty: vt: always invoke vc->vc_sw->con_resize callback Date: Mon, 24 May 2021 17:25:20 +0200 Message-Id: <20210524152325.298259254@linuxfoundation.org> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210524152324.158146731@linuxfoundation.org> References: <20210524152324.158146731@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@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/console/fbcon.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) --- a/drivers/tty/vt/vt.c +++ b/drivers/tty/vt/vt.c @@ -838,7 +838,7 @@ 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/console/fbcon.c +++ b/drivers/video/console/fbcon.c @@ -1986,7 +1986,7 @@ 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);