From patchwork Mon Aug 31 10:37:00 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Tetsuo Handa X-Patchwork-Id: 11747535 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 8220713B6 for ; Tue, 1 Sep 2020 07:32:22 +0000 (UTC) Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 6B17B206CD for ; Tue, 1 Sep 2020 07:32:22 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6B17B206CD Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=i-love.sakura.ne.jp Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=dri-devel-bounces@lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 3B9E36E5D1; Tue, 1 Sep 2020 07:31:58 +0000 (UTC) X-Original-To: dri-devel@lists.freedesktop.org Delivered-To: dri-devel@lists.freedesktop.org Received: from www262.sakura.ne.jp (www262.sakura.ne.jp [202.181.97.72]) by gabe.freedesktop.org (Postfix) with ESMTPS id 1409C89FC5 for ; Mon, 31 Aug 2020 10:37:11 +0000 (UTC) Received: from fsav103.sakura.ne.jp (fsav103.sakura.ne.jp [27.133.134.230]) by www262.sakura.ne.jp (8.15.2/8.15.2) with ESMTP id 07VAb8mb000380; Mon, 31 Aug 2020 19:37:08 +0900 (JST) (envelope-from penguin-kernel@i-love.sakura.ne.jp) Received: from www262.sakura.ne.jp (202.181.97.72) by fsav103.sakura.ne.jp (F-Secure/fsigk_smtp/550/fsav103.sakura.ne.jp); Mon, 31 Aug 2020 19:37:08 +0900 (JST) X-Virus-Status: clean(F-Secure/fsigk_smtp/550/fsav103.sakura.ne.jp) Received: from [192.168.1.9] (M106072142033.v4.enabler.ne.jp [106.72.142.33]) (authenticated bits=0) by www262.sakura.ne.jp (8.15.2/8.15.2) with ESMTPSA id 07VAb2OO099982 (version=TLSv1.2 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Mon, 31 Aug 2020 19:37:08 +0900 (JST) (envelope-from penguin-kernel@i-love.sakura.ne.jp) Subject: [PATCH v2 (resend)] video: fbdev: fix OOB read in vga_8planes_imageblit() References: <11ad8786-e407-3289-8bd9-2745c4834718@i-love.sakura.ne.jp> To: Greg Kroah-Hartman From: Tetsuo Handa X-Forwarded-Message-Id: <11ad8786-e407-3289-8bd9-2745c4834718@i-love.sakura.ne.jp> Message-ID: <90b55ec3-d5b0-3307-9f7c-7ff5c5fd6ad3@i-love.sakura.ne.jp> Date: Mon, 31 Aug 2020 19:37:00 +0900 User-Agent: Mozilla/5.0 (Windows NT 6.3; Win64; x64; rv:68.0) Gecko/20100101 Thunderbird/68.12.0 MIME-Version: 1.0 In-Reply-To: <11ad8786-e407-3289-8bd9-2745c4834718@i-love.sakura.ne.jp> Content-Language: en-US X-Mailman-Approved-At: Tue, 01 Sep 2020 07:31:54 +0000 X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Linux Fbdev development list , DRI , Bartlomiej Zolnierkiewicz Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" syzbot is reporting OOB read at vga_8planes_imageblit() [1], for "cdat[y] >> 4" can become a negative value due to "const char *cdat". [1] https://syzkaller.appspot.com/bug?id=0d7a0da1557dcd1989e00cb3692b26d4173b4132 Reported-by: syzbot Signed-off-by: Tetsuo Handa --- drivers/video/fbdev/vga16fb.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/video/fbdev/vga16fb.c b/drivers/video/fbdev/vga16fb.c index a20eeb8308ff..578d3541e3d6 100644 --- a/drivers/video/fbdev/vga16fb.c +++ b/drivers/video/fbdev/vga16fb.c @@ -1121,7 +1121,7 @@ static void vga_8planes_imageblit(struct fb_info *info, const struct fb_image *i char oldop = setop(0); char oldsr = setsr(0); char oldmask = selectmask(); - const char *cdat = image->data; + const unsigned char *cdat = image->data; u32 dx = image->dx; char __iomem *where; int y;