From patchwork Tue Dec 3 17:46:32 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Imre Deak X-Patchwork-Id: 13892783 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 BCD93E74AC9 for ; Tue, 3 Dec 2024 17:45:56 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 6481D10EAF3; Tue, 3 Dec 2024 17:45:56 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=intel.com header.i=@intel.com header.b="VJbU0UBo"; dkim-atps=neutral Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.19]) by gabe.freedesktop.org (Postfix) with ESMTPS id 8D99310EAF0; Tue, 3 Dec 2024 17:45:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1733247955; x=1764783955; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=tqb7zp0+menYzgwWCTZOrH67+2p8i2CZtaOqiZ0YxJk=; b=VJbU0UBo1KbdhtlRJtmGnI3jI7hfiOzsT1ZpsgkkXcMwZfRbF7ttPmDR c20MaDJLpHrT7t2O2OokR2ctvx/do7RJIyNr5SgyFgKArus2K3bGILdXl 2DsvOML98NctSsUizoUqbFDogwdz7P7i/vuXbRnNRApBStycHahn/Fir6 upVbhAcvhmxnlkKwasjCildVGZUBm40xcym6VkHRsPvOle3Vpg05El7nf cQGLD95QuTXItq/wHlTvn0D1b0MtzznElCQXppxRTLytasFqvEqCWBiWv gc5FT9mSKTD909GZkUIbIdHTpWR0uUw/DKzHItMj1bk/IQoDDAgAJlagJ A==; X-CSE-ConnectionGUID: tSEXMSrzTOqHIbfRvFNijQ== X-CSE-MsgGUID: 7p+Lh/XRRNSlR4GwKGoO8w== X-IronPort-AV: E=McAfee;i="6700,10204,11275"; a="33355504" X-IronPort-AV: E=Sophos;i="6.12,205,1728975600"; d="scan'208";a="33355504" Received: from fmviesa003.fm.intel.com ([10.60.135.143]) by orvoesa111.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 03 Dec 2024 09:45:54 -0800 X-CSE-ConnectionGUID: GTcp+KC8RC64mDWhKpQCDA== X-CSE-MsgGUID: s4gziCP8Sqy0Cy0h7TvDRA== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.12,205,1728975600"; d="scan'208";a="97569894" Received: from ideak-desk.fi.intel.com ([10.237.72.78]) by fmviesa003-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 03 Dec 2024 09:45:53 -0800 From: Imre Deak To: intel-gfx@lists.freedesktop.org Cc: dri-devel@lists.freedesktop.org, Lyude Paul Subject: [PATCH v2 4/7] drm/dp_mst: Fix down request message timeout handling Date: Tue, 3 Dec 2024 19:46:32 +0200 Message-ID: <20241203174632.2941402-1-imre.deak@intel.com> X-Mailer: git-send-email 2.44.2 In-Reply-To: <20241203160223.2926014-5-imre.deak@intel.com> References: <20241203160223.2926014-5-imre.deak@intel.com> MIME-Version: 1.0 X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" If receiving a reply for an MST down request message times out, the thread receiving the reply in drm_dp_mst_handle_down_rep() could try to dereference the drm_dp_sideband_msg_tx txmsg request message after the thread waiting for the reply - calling drm_dp_mst_wait_tx_reply() - has timed out and freed txmsg, hence leading to a use-after-free in drm_dp_mst_handle_down_rep(). Prevent the above by holding the drm_dp_mst_topology_mgr::qlock in drm_dp_mst_handle_down_rep() for the whole duration txmsg is looked up from the request list and dereferenced. v2: Fix unlocking mgr->qlock after verify_rx_request_type() fails. Cc: Lyude Paul Signed-off-by: Imre Deak --- drivers/gpu/drm/display/drm_dp_mst_topology.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) diff --git a/drivers/gpu/drm/display/drm_dp_mst_topology.c b/drivers/gpu/drm/display/drm_dp_mst_topology.c index 6ec8680998d5a..ab21855d5c0f7 100644 --- a/drivers/gpu/drm/display/drm_dp_mst_topology.c +++ b/drivers/gpu/drm/display/drm_dp_mst_topology.c @@ -3984,9 +3984,9 @@ static int drm_dp_mst_handle_down_rep(struct drm_dp_mst_topology_mgr *mgr) /* find the message */ mutex_lock(&mgr->qlock); + txmsg = list_first_entry_or_null(&mgr->tx_msg_downq, struct drm_dp_sideband_msg_tx, next); - mutex_unlock(&mgr->qlock); /* Were we actually expecting a response, and from this mstb? */ if (!txmsg || txmsg->dst != mstb) { @@ -3995,11 +3995,17 @@ static int drm_dp_mst_handle_down_rep(struct drm_dp_mst_topology_mgr *mgr) hdr = &msg->initial_hdr; drm_dbg_kms(mgr->dev, "Got MST reply with no msg %p %d %d %02x %02x\n", mstb, hdr->seqno, hdr->lct, hdr->rad[0], msg->msg[0]); + + mutex_unlock(&mgr->qlock); + goto out_clear_reply; } - if (!verify_rx_request_type(mgr, txmsg, msg)) + if (!verify_rx_request_type(mgr, txmsg, msg)) { + mutex_unlock(&mgr->qlock); + goto out_clear_reply; + } drm_dp_sideband_parse_reply(mgr, msg, &txmsg->reply); @@ -4013,9 +4019,9 @@ static int drm_dp_mst_handle_down_rep(struct drm_dp_mst_topology_mgr *mgr) txmsg->reply.u.nak.nak_data); } - mutex_lock(&mgr->qlock); txmsg->state = DRM_DP_SIDEBAND_TX_RX; list_del(&txmsg->next); + mutex_unlock(&mgr->qlock); wake_up_all(&mgr->tx_waitq);