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=-9.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, 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 6BC77C282C8 for ; Mon, 28 Jan 2019 15:43:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2EC912171F for ; Mon, 28 Jan 2019 15:43:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1548690226; bh=6s46nmun2gsRic+OXbbgyB83rjznMWO8S+LSv7OcdEo=; h=From:To:Cc:Subject:Date:List-ID:From; b=D9ud3QG8ZV6l5J4/7fotOUTgQY9KNpGljxcEcrOj8TGHCY5giX1tKocD9xPUMBiE+ svkKVFFOwZLXtiWufLBzQZ47hywLbPzlhLy9XCUwL7MRUHHO+noFRVj8/gNyhkumKS dDLa06xkE0pmzyE8sCDFh3PkdAGx0gblLICir/K0= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726982AbfA1Pno (ORCPT ); Mon, 28 Jan 2019 10:43:44 -0500 Received: from mail.kernel.org ([198.145.29.99]:56910 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726647AbfA1Pno (ORCPT ); Mon, 28 Jan 2019 10:43:44 -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 0D2EF20880; Mon, 28 Jan 2019 15:43:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1548690223; bh=6s46nmun2gsRic+OXbbgyB83rjznMWO8S+LSv7OcdEo=; h=From:To:Cc:Subject:Date:From; b=zx/RA/8ct7sZtDNKv+dRAR1dAvfDIF3T5TU+NiVKv4AtftHV1SpRrTtBeNqWIbuLY XB0SASWqXKxBbcPYNYIZK4a8QPK3IgMLIuAIgEu/hbXjSDICNG1gdZktqsZ3LEDQHK kD9UciUo9jbv64MlJW/59oHnBU48nN3kw/RVvwL8= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: "Gustavo A. R. Silva" , Daniel Vetter , Sasha Levin Subject: [PATCH AUTOSEL 4.20 001/304] drm/bufs: Fix Spectre v1 vulnerability Date: Mon, 28 Jan 2019 10:38:38 -0500 Message-Id: <20190128154341.47195-1-sashal@kernel.org> X-Mailer: git-send-email 2.19.1 MIME-Version: 1.0 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: "Gustavo A. R. Silva" [ Upstream commit a37805098900a6e73a55b3a43b7d3bcd987bb3f4 ] idx can be indirectly controlled by user-space, hence leading to a potential exploitation of the Spectre variant 1 vulnerability. This issue was detected with the help of Smatch: drivers/gpu/drm/drm_bufs.c:1420 drm_legacy_freebufs() warn: potential spectre issue 'dma->buflist' [r] (local cap) Fix this by sanitizing idx before using it to index dma->buflist Notice that given that speculation windows are large, the policy is to kill the speculation on the first load and not worry if it can be completed with a dependent load/store [1]. [1] https://marc.info/?l=linux-kernel&m=152449131114778&w=2 Signed-off-by: Gustavo A. R. Silva Signed-off-by: Daniel Vetter Link: https://patchwork.freedesktop.org/patch/msgid/20181016095549.GA23586@embeddedor.com Signed-off-by: Sasha Levin --- drivers/gpu/drm/drm_bufs.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/gpu/drm/drm_bufs.c b/drivers/gpu/drm/drm_bufs.c index 7412acaf3cde..d7d10cabb9bb 100644 --- a/drivers/gpu/drm/drm_bufs.c +++ b/drivers/gpu/drm/drm_bufs.c @@ -36,6 +36,8 @@ #include #include "drm_legacy.h" +#include + static struct drm_map_list *drm_find_matching_map(struct drm_device *dev, struct drm_local_map *map) { @@ -1417,6 +1419,7 @@ int drm_legacy_freebufs(struct drm_device *dev, void *data, idx, dma->buf_count - 1); return -EINVAL; } + idx = array_index_nospec(idx, dma->buf_count); buf = dma->buflist[idx]; if (buf->file_priv != file_priv) { DRM_ERROR("Process %d freeing buffer not owned\n", -- 2.19.1