From patchwork Wed Dec 4 13:20:07 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Imre Deak X-Patchwork-Id: 13893782 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org 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 smtp.lore.kernel.org (Postfix) with ESMTPS id AADDCE7716E for ; Wed, 4 Dec 2024 13:19:31 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id ABC0210ED05; Wed, 4 Dec 2024 13:19:30 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=intel.com header.i=@intel.com header.b="nvR7HkZE"; dkim-atps=neutral Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.8]) by gabe.freedesktop.org (Postfix) with ESMTPS id 7D66810E0D1; Wed, 4 Dec 2024 13:19:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1733318369; x=1764854369; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=Bl3YRY2ZNAyUOBZvgqu14yu+mKsPPDUgR1HwrQGFpi8=; b=nvR7HkZENd4FWl5vF+kw0dgOgYgNr8U9mGxyGaNaPgDy+0/qnvxWMig8 JUVXgh/r63/3y5+TcR2UWSoT1zS0rRAKyvZL0ZlianmB/gZzL/vAXJZWx 7ae/6OyL5UiEn3G3Eq9Tbj0a8Vx2K9Zg2txoy5dIYhuq/ZHAM9NXjVMTe mZiVkBYGeDzEGnivyISS3Zc5Rt4WRa0p+g4OVylev3JCk8Q9d3NA/lgfI mX1DDP554HRvknkMPriIeSMP71dITxfiwx/wHew7kJlb+8etpAQpYDCJY EFFTZ/Ol4pGzKxhYWXvVtUGD4g96j611p0Qc9C7I6JRYe+TlJ7Q8y+Htg Q==; X-CSE-ConnectionGUID: PuNcHz+JTISiSxCOtdCwDg== X-CSE-MsgGUID: EtygWjIJQa+q5FOHubrVdg== X-IronPort-AV: E=McAfee;i="6700,10204,11276"; a="51114460" X-IronPort-AV: E=Sophos;i="6.12,207,1728975600"; d="scan'208";a="51114460" Received: from orviesa001.jf.intel.com ([10.64.159.141]) by fmvoesa102.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 04 Dec 2024 05:19:29 -0800 X-CSE-ConnectionGUID: /78+7sWGQ7OBEeaBbF1TEw== X-CSE-MsgGUID: RiDIH8yNQyKXFyuMpCkoPw== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.12,207,1728975600"; d="scan'208";a="131218557" Received: from ideak-desk.fi.intel.com ([10.237.72.78]) by smtpauth.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 04 Dec 2024 05:19:27 -0800 From: Imre Deak To: intel-gfx@lists.freedesktop.org Cc: dri-devel@lists.freedesktop.org, Lyude Paul Subject: [PATCH v2 5/7] drm/dp_mst: Ensure mst_primary pointer is valid in drm_dp_mst_handle_up_req() Date: Wed, 4 Dec 2024 15:20:07 +0200 Message-ID: <20241204132007.3132494-1-imre.deak@intel.com> X-Mailer: git-send-email 2.44.2 In-Reply-To: <20241203160223.2926014-6-imre.deak@intel.com> References: <20241203160223.2926014-6-imre.deak@intel.com> MIME-Version: 1.0 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: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" While receiving an MST up request message from one thread in drm_dp_mst_handle_up_req(), the MST topology could be removed from another thread via drm_dp_mst_topology_mgr_set_mst(false), freeing mst_primary and setting drm_dp_mst_topology_mgr::mst_primary to NULL. This could lead to a NULL deref/use-after-free of mst_primary in drm_dp_mst_handle_up_req(). Avoid the above by holding a reference for mst_primary in drm_dp_mst_handle_up_req() while it's used. v2: Fix kfreeing the request if getting an mst_primary reference fails. Cc: Lyude Paul Reviewed-by: Lyude Paul (v1) Signed-off-by: Imre Deak --- drivers/gpu/drm/display/drm_dp_mst_topology.c | 24 ++++++++++++++----- 1 file changed, 18 insertions(+), 6 deletions(-) diff --git a/drivers/gpu/drm/display/drm_dp_mst_topology.c b/drivers/gpu/drm/display/drm_dp_mst_topology.c index 895c78806f0c5..7a0e757b712c7 100644 --- a/drivers/gpu/drm/display/drm_dp_mst_topology.c +++ b/drivers/gpu/drm/display/drm_dp_mst_topology.c @@ -4105,9 +4105,10 @@ static void drm_dp_mst_up_req_work(struct work_struct *work) static int drm_dp_mst_handle_up_req(struct drm_dp_mst_topology_mgr *mgr) { struct drm_dp_pending_up_req *up_req; + struct drm_dp_mst_branch *mst_primary; if (!drm_dp_get_one_sb_msg(mgr, true, NULL)) - goto out; + goto out_clear_reply; if (!mgr->up_req_recv.have_eomt) return 0; @@ -4125,10 +4126,19 @@ static int drm_dp_mst_handle_up_req(struct drm_dp_mst_topology_mgr *mgr) drm_dbg_kms(mgr->dev, "Received unknown up req type, ignoring: %x\n", up_req->msg.req_type); kfree(up_req); - goto out; + goto out_clear_reply; + } + + mutex_lock(&mgr->lock); + mst_primary = mgr->mst_primary; + if (!mst_primary || !drm_dp_mst_topology_try_get_mstb(mst_primary)) { + mutex_unlock(&mgr->lock); + kfree(up_req); + goto out_clear_reply; } + mutex_unlock(&mgr->lock); - drm_dp_send_up_ack_reply(mgr, mgr->mst_primary, up_req->msg.req_type, + drm_dp_send_up_ack_reply(mgr, mst_primary, up_req->msg.req_type, false); if (up_req->msg.req_type == DP_CONNECTION_STATUS_NOTIFY) { @@ -4145,13 +4155,13 @@ static int drm_dp_mst_handle_up_req(struct drm_dp_mst_topology_mgr *mgr) conn_stat->peer_device_type); mutex_lock(&mgr->probe_lock); - handle_csn = mgr->mst_primary->link_address_sent; + handle_csn = mst_primary->link_address_sent; mutex_unlock(&mgr->probe_lock); if (!handle_csn) { drm_dbg_kms(mgr->dev, "Got CSN before finish topology probing. Skip it."); kfree(up_req); - goto out; + goto out_put_primary; } } else if (up_req->msg.req_type == DP_RESOURCE_STATUS_NOTIFY) { const struct drm_dp_resource_status_notify *res_stat = @@ -4168,7 +4178,9 @@ static int drm_dp_mst_handle_up_req(struct drm_dp_mst_topology_mgr *mgr) mutex_unlock(&mgr->up_req_lock); queue_work(system_long_wq, &mgr->up_req_work); -out: +out_put_primary: + drm_dp_mst_topology_put_mstb(mst_primary); +out_clear_reply: memset(&mgr->up_req_recv, 0, sizeof(struct drm_dp_sideband_msg_rx)); return 0; }