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=-10.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, 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 91B6DC43603 for ; Tue, 10 Dec 2019 21:04:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 59F20214AF for ; Tue, 10 Dec 2019 21:04:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1576011851; bh=VQ5a4xBBMy6ZGg8kyYiUVjmv92AEpnGHsls0CSS71jk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=0QXxn/RPHv8Nu8YmbvykJ3yBJ6lVNSuGJ1OiVUcSL2zDj6POL/OUUB13snhyJ5pou 8Pj6roNlFmrWE2bLzYWhDeijgn4X3zctlOWIJCMHqc8fZcDfqq+J0i0klKJyjq4X3b +GjbVoG0kovv07i/+0wJukbH7ArBy8Gs2ruBmwUk= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726986AbfLJVEJ (ORCPT ); Tue, 10 Dec 2019 16:04:09 -0500 Received: from mail.kernel.org ([198.145.29.99]:48864 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726717AbfLJVEJ (ORCPT ); Tue, 10 Dec 2019 16:04:09 -0500 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id E76E9206EC; Tue, 10 Dec 2019 21:04:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1576011848; bh=VQ5a4xBBMy6ZGg8kyYiUVjmv92AEpnGHsls0CSS71jk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=PtY7XvbT+Cw7dIpZUlRVZpWvMDkqEytfH7oXA/gP8Y+ZORMowdMDUCxFjbcadBjiE V1+2BvlED74IvHGoormdAz6tev4aEhfLdzAVhP0mmHR16m6ICra/7yJgFihEodKH71 6FSDppgGE22+4jj0AKbav1TBfwcJyv4qnHuo4g4A= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Dan Carpenter , =?UTF-8?q?Noralf=20Tr=C3=B8nnes?= , Sasha Levin , dri-devel@lists.freedesktop.org Subject: [PATCH AUTOSEL 5.4 004/350] drm/mipi-dbi: fix a loop in debugfs code Date: Tue, 10 Dec 2019 15:58:16 -0500 Message-Id: <20191210210402.8367-4-sashal@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20191210210402.8367-1-sashal@kernel.org> References: <20191210210402.8367-1-sashal@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Dan Carpenter [ Upstream commit d72cf01f410aa09868d98b672f3f92328c96b32d ] This code will likely crash if we try to do a zero byte write. The code looks like this: /* strip trailing whitespace */ for (i = count - 1; i > 0; i--) if (isspace(buf[i])) ... We're writing zero bytes so count = 0. You would think that "count - 1" would be negative one, but because "i" is unsigned it is a large positive numer instead. The "i > 0" condition is true and the "buf[i]" access will be out of bounds. The fix is to make "i" signed and now everything works as expected. The upper bound of "count" is capped in __kernel_write() at MAX_RW_COUNT so we don't have to worry about it being higher than INT_MAX. Fixes: 02dd95fe3169 ("drm/tinydrm: Add MIPI DBI support") Signed-off-by: Dan Carpenter [noralf: Adjust title] Signed-off-by: Noralf Trønnes Link: https://patchwork.freedesktop.org/patch/msgid/20190821072456.GJ26957@mwanda Signed-off-by: Sasha Levin --- drivers/gpu/drm/drm_mipi_dbi.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/drivers/gpu/drm/drm_mipi_dbi.c b/drivers/gpu/drm/drm_mipi_dbi.c index 1961f713aaab4..c4ee2709a6f32 100644 --- a/drivers/gpu/drm/drm_mipi_dbi.c +++ b/drivers/gpu/drm/drm_mipi_dbi.c @@ -1187,8 +1187,7 @@ static ssize_t mipi_dbi_debugfs_command_write(struct file *file, struct mipi_dbi_dev *dbidev = m->private; u8 val, cmd = 0, parameters[64]; char *buf, *pos, *token; - unsigned int i; - int ret, idx; + int i, ret, idx; if (!drm_dev_enter(&dbidev->drm, &idx)) return -ENODEV; -- 2.20.1