From nobody Fri Sep 5 20:06:16 2025 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id F0795C32772 for ; Tue, 23 Aug 2022 11:42:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1351086AbiHWLmV (ORCPT ); Tue, 23 Aug 2022 07:42:21 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58988 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1358150AbiHWLhD (ORCPT ); Tue, 23 Aug 2022 07:37:03 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D9128C8888; Tue, 23 Aug 2022 02:27:57 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 2873CB81C95; Tue, 23 Aug 2022 09:27:55 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 65F01C43470; Tue, 23 Aug 2022 09:27:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1661246873; bh=himHa72SbR58BlQGvStzlVlxCP07VtgiIqZ7m2ZiR40=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ixEjeh1X9l7Msk6zj+FKVJufPK0dH5O6h/wXLdL/Kuj4dXkfaybIsYZUx8KntsygM Z0+vRmLDvUpZij6VitW0L7Wfe81xgDepYnSppkNKFjkYq95/7el1JoLYdsvFieJt47 /35WTs2g3RZACGDdc/+TjPwESwGR5ObldNpJHuCQ= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Zheyu Ma , Helge Deller , Sasha Levin Subject: [PATCH 5.4 247/389] video: fbdev: s3fb: Check the size of screen before memset_io() Date: Tue, 23 Aug 2022 10:25:25 +0200 Message-Id: <20220823080125.895945189@linuxfoundation.org> X-Mailer: git-send-email 2.37.2 In-Reply-To: <20220823080115.331990024@linuxfoundation.org> References: <20220823080115.331990024@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" From: Zheyu Ma [ Upstream commit 6ba592fa014f21f35a8ee8da4ca7b95a018f13e8 ] In the function s3fb_set_par(), the value of 'screen_size' is calculated by the user input. If the user provides the improper value, the value of 'screen_size' may larger than 'info->screen_size', which may cause the following bug: [ 54.083733] BUG: unable to handle page fault for address: ffffc900030000= 00 [ 54.083742] #PF: supervisor write access in kernel mode [ 54.083744] #PF: error_code(0x0002) - not-present page [ 54.083760] RIP: 0010:memset_orig+0x33/0xb0 [ 54.083782] Call Trace: [ 54.083788] s3fb_set_par+0x1ec6/0x4040 [ 54.083806] fb_set_var+0x604/0xeb0 [ 54.083836] do_fb_ioctl+0x234/0x670 Fix the this by checking the value of 'screen_size' before memset_io(). Fixes: a268422de8bf ("fbdev driver for S3 Trio/Virge") Signed-off-by: Zheyu Ma Signed-off-by: Helge Deller Signed-off-by: Sasha Levin --- drivers/video/fbdev/s3fb.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/video/fbdev/s3fb.c b/drivers/video/fbdev/s3fb.c index be16c349c10f..228e5ee7a547 100644 --- a/drivers/video/fbdev/s3fb.c +++ b/drivers/video/fbdev/s3fb.c @@ -902,6 +902,8 @@ static int s3fb_set_par(struct fb_info *info) value =3D clamp((htotal + hsstart + 1) / 2 + 2, hsstart + 4, htotal + 1); svga_wcrt_multi(par->state.vgabase, s3_dtpc_regs, value); =20 + if (screen_size > info->screen_size) + screen_size =3D info->screen_size; memset_io(info->screen_base, 0x00, screen_size); /* Device and screen back on */ svga_wcrt_mask(par->state.vgabase, 0x17, 0x80, 0x80); --=20 2.35.1