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=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, 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 493C9C2BBC7 for ; Sat, 11 Apr 2020 12:27:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 233B920644 for ; Sat, 11 Apr 2020 12:27:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1586608052; bh=iGsE+U9DnD/v9N3Au/gt5Nukp6ciVSTUMneMAPVjTu0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=XHSZipsMDJ4oavlEAua0GG4RjDSzqLP2voTnHqkQ5O/6/LCSQ0ebYxuLdkCLl1gMa VbNIIYRi44lno9D9Mg2LG737a3lHuUWD36QfdsUb/btkzQhBv97Z/M2E958ECkRUOP JYZcRfapqr2Ij3Kz8Jp5lpHQPTtWP016XlUaBsLQ= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726973AbgDKMOD (ORCPT ); Sat, 11 Apr 2020 08:14:03 -0400 Received: from mail.kernel.org ([198.145.29.99]:47290 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726824AbgDKMOC (ORCPT ); Sat, 11 Apr 2020 08:14:02 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 6597C2166E; Sat, 11 Apr 2020 12:14:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1586607242; bh=iGsE+U9DnD/v9N3Au/gt5Nukp6ciVSTUMneMAPVjTu0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=O+2MpP16fX5cSiNz8UmH2vlfhCeVurkiW3rGG+yEn3OBagNUVPwJNQtBBAh20ow03 fdBc1aDkTZ5xX2FxiaxdYk0ne5/svgc4przJTSY9fGmWSssEpwkta+u42jumBxfxsC w934MKbIunfv/LEJzuxcISxEVDqczE7P+TQ3PRCQ= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, syzbot+732528bae351682f1f27@syzkaller.appspotmail.com, Qiujun Huang , Sam Ravnborg , Daniel Vetter Subject: [PATCH 4.14 31/38] fbcon: fix null-ptr-deref in fbcon_switch Date: Sat, 11 Apr 2020 14:09:15 +0200 Message-Id: <20200411115440.870083532@linuxfoundation.org> X-Mailer: git-send-email 2.26.0 In-Reply-To: <20200411115437.795556138@linuxfoundation.org> References: <20200411115437.795556138@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Qiujun Huang commit b139f8b00db4a8ea75a4174346eafa48041aa489 upstream. Set logo_shown to FBCON_LOGO_CANSHOW when the vc was deallocated. syzkaller report: https://lkml.org/lkml/2020/3/27/403 general protection fault, probably for non-canonical address 0xdffffc000000006c: 0000 [#1] SMP KASAN KASAN: null-ptr-deref in range [0x0000000000000360-0x0000000000000367] RIP: 0010:fbcon_switch+0x28f/0x1740 drivers/video/fbdev/core/fbcon.c:2260 Call Trace: redraw_screen+0x2a8/0x770 drivers/tty/vt/vt.c:1008 vc_do_resize+0xfe7/0x1360 drivers/tty/vt/vt.c:1295 fbcon_init+0x1221/0x1ab0 drivers/video/fbdev/core/fbcon.c:1219 visual_init+0x305/0x5c0 drivers/tty/vt/vt.c:1062 do_bind_con_driver+0x536/0x890 drivers/tty/vt/vt.c:3542 do_take_over_console+0x453/0x5b0 drivers/tty/vt/vt.c:4122 do_fbcon_takeover+0x10b/0x210 drivers/video/fbdev/core/fbcon.c:588 fbcon_fb_registered+0x26b/0x340 drivers/video/fbdev/core/fbcon.c:3259 do_register_framebuffer drivers/video/fbdev/core/fbmem.c:1664 [inline] register_framebuffer+0x56e/0x980 drivers/video/fbdev/core/fbmem.c:1832 dlfb_usb_probe.cold+0x1743/0x1ba3 drivers/video/fbdev/udlfb.c:1735 usb_probe_interface+0x310/0x800 drivers/usb/core/driver.c:374 accessing vc_cons[logo_shown].d->vc_top causes the bug. Reported-by: syzbot+732528bae351682f1f27@syzkaller.appspotmail.com Signed-off-by: Qiujun Huang Acked-by: Sam Ravnborg Cc: stable@vger.kernel.org Signed-off-by: Daniel Vetter Link: https://patchwork.freedesktop.org/patch/msgid/20200329085647.25133-1-hqjagain@gmail.com Signed-off-by: Greg Kroah-Hartman --- drivers/video/fbdev/core/fbcon.c | 3 +++ 1 file changed, 3 insertions(+) --- a/drivers/video/fbdev/core/fbcon.c +++ b/drivers/video/fbdev/core/fbcon.c @@ -1221,6 +1221,9 @@ finished: if (!con_is_bound(&fb_con)) fbcon_exit(); + if (vc->vc_num == logo_shown) + logo_shown = FBCON_LOGO_CANSHOW; + return; }