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=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 76A4FC43603 for ; Tue, 10 Dec 2019 21:27:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 39D67206D5 for ; Tue, 10 Dec 2019 21:27:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1576013255; bh=1TL1cfOTkjPwCJCaGLP0Z6byKDzAchxlwBZbQAlNnoA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=ea3XgE9qKMn3nmy9rer9IZvHJB/CsLKeWzfUAiPF6jC7p4F4ifhh3HlQBS7fORMM9 IIHtN2PwBIxLGeVGz4OqDs7Z0o9MK9MSZu6A8bOk6/TAfrXN0b40IsuuP1DN6poJbQ oLbJFfLMBLuuqMQJRg2zI9/dlRBAh/ibJXpImFpw= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728980AbfLJV1e (ORCPT ); Tue, 10 Dec 2019 16:27:34 -0500 Received: from mail.kernel.org ([198.145.29.99]:55876 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728889AbfLJVZR (ORCPT ); Tue, 10 Dec 2019 16:25:17 -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 84AEA207FF; Tue, 10 Dec 2019 21:25:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1576013116; bh=1TL1cfOTkjPwCJCaGLP0Z6byKDzAchxlwBZbQAlNnoA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=DnAmdD6Ky6wIj0bBYUt1xR52X27tDj+oJ70oQ7VZ/Inmot+/D9WhkJRROu03d+zNr S1qWS+dcxVN1uzRSAEFg6gKd6CPgZbBKyVh90rUKN2/87JJyzmtkRi6l9ze9R7aqmE 0PBID3oUrkBAWcQ9ztg0hMfAr81fAn6fKkqedswQ= 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 5.3 003/292] drm/mipi-dbi: fix a loop in debugfs code Date: Tue, 10 Dec 2019 16:20:22 -0500 Message-Id: <20191210212511.11392-3-sashal@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20191210212511.11392-1-sashal@kernel.org> References: <20191210212511.11392-1-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: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@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/tinydrm/mipi-dbi.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/drivers/gpu/drm/tinydrm/mipi-dbi.c b/drivers/gpu/drm/tinydrm/mipi-dbi.c index ca9da654fc6f4..d6b7c706c674b 100644 --- a/drivers/gpu/drm/tinydrm/mipi-dbi.c +++ b/drivers/gpu/drm/tinydrm/mipi-dbi.c @@ -1033,8 +1033,7 @@ static ssize_t mipi_dbi_debugfs_command_write(struct file *file, struct mipi_dbi *mipi = 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(&mipi->drm, &idx)) return -ENODEV; -- 2.20.1