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=-7.5 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, 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 70A9EC43441 for ; Mon, 19 Nov 2018 16:38:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 38E4E213A2 for ; Mon, 19 Nov 2018 16:38:13 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="2voMEVeM" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 38E4E213A2 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linuxfoundation.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732412AbeKTDCU (ORCPT ); Mon, 19 Nov 2018 22:02:20 -0500 Received: from mail.kernel.org ([198.145.29.99]:34550 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731789AbeKTDCT (ORCPT ); Mon, 19 Nov 2018 22:02:19 -0500 Received: from localhost (5356596B.cm-6-7b.dynamic.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id DDE01208E4; Mon, 19 Nov 2018 16:38:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1542645490; bh=rsxvSKBPFIRTt6EC6XsExlkkLBOqYoUUbovC7ApnLvU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=2voMEVeMgfI5eRbMtxp2vvq3l3CcWKxB1whQFebBytn+ner79oqkmCjSH7zLcipmn O1eHNKvtFIt5ja4ehMlmx6iYvEGDO9QCtWKxhJfjODt2CW49p9Q5UvL/zUWSUErVB7 EQzDKN/Zc+4E3Nr6JxXu2rASgihhP8VkPE19BUcc= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Lyude Paul , Stanislav Lisovskiy Subject: [PATCH 4.19 181/205] drm/dp_mst: Check if primary mstb is null Date: Mon, 19 Nov 2018 17:28:08 +0100 Message-Id: <20181119162641.267375166@linuxfoundation.org> X-Mailer: git-send-email 2.19.1 In-Reply-To: <20181119162616.586062722@linuxfoundation.org> References: <20181119162616.586062722@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.19-stable review patch. If anyone has any objections, please let me know. ------------------ From: Stanislav Lisovskiy commit 23d8003907d094f77cf959228e2248d6db819fa7 upstream. Unfortunately drm_dp_get_mst_branch_device which is called from both drm_dp_mst_handle_down_rep and drm_dp_mst_handle_up_rep seem to rely on that mgr->mst_primary is not NULL, which seem to be wrong as it can be cleared with simultaneous mode set, if probing fails or in other case. mgr->lock mutex doesn't protect against that as it might just get assigned to NULL right before, not simultaneously. There are currently bugs 107738, 108616 bugs which crash in drm_dp_get_mst_branch_device, caused by this issue. v2: Refactored the code, as it was nicely noticed. Fixed Bugzilla bug numbers(second was 108616, but not 108816) and added links. [changed title and added stable cc] Signed-off-by: Lyude Paul Signed-off-by: Stanislav Lisovskiy Cc: stable@vger.kernel.org Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=108616 Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=107738 Link: https://patchwork.freedesktop.org/patch/msgid/20181109090012.24438-1-stanislav.lisovskiy@intel.com Signed-off-by: Greg Kroah-Hartman --- drivers/gpu/drm/drm_dp_mst_topology.c | 3 +++ 1 file changed, 3 insertions(+) --- a/drivers/gpu/drm/drm_dp_mst_topology.c +++ b/drivers/gpu/drm/drm_dp_mst_topology.c @@ -1274,6 +1274,9 @@ static struct drm_dp_mst_branch *drm_dp_ mutex_lock(&mgr->lock); mstb = mgr->mst_primary; + if (!mstb) + goto out; + for (i = 0; i < lct - 1; i++) { int shift = (i % 2) ? 0 : 4; int port_num = (rad[i / 2] >> shift) & 0xf;