From patchwork Tue Dec 3 16:02:17 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Imre Deak X-Patchwork-Id: 13892659 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 01575E74AC2 for ; Tue, 3 Dec 2024 16:01:51 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id A277410EA83; Tue, 3 Dec 2024 16:01:51 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=intel.com header.i=@intel.com header.b="A+udgN99"; dkim-atps=neutral Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.14]) by gabe.freedesktop.org (Postfix) with ESMTPS id DEB5D10EA83; Tue, 3 Dec 2024 16:01:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1733241710; x=1764777710; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=AmnQe6A3KxtcW8XP/QhfkCqFZwG4vY1KZmdy7VCDCSE=; b=A+udgN999fxFEAutII66qrlAxpUVHo6+cPQzJZdw+AqSzRK5iNris9Te BRADmyJDcO+skCD0NoeUyHTSQFcpmYJn1BiI+60hvgSMTtR4nFUAPMEnB 9NMKwCihKthr9hgct5dEsDqz8HuEKOMAaiiiYb5AOWQa2GPuQXDlynxw7 HnDTRanRqg7Alk6p/c03I3revc4nF8Ex0Wb0p4XRgq3GRO6t+XS9xOvNu LYPpNzQ0G1vF9vLR5qpazembV/YMZC4reCI0eR9H6uCIgPDdofJB0oqsB xOmjacJYtxQik1ceALLsD4ROpPjspM0Y1wI6yII+/T8h1YMIsPtpuBqbh Q==; X-CSE-ConnectionGUID: rRF6FzJyTsSVA+TmCqxi5A== X-CSE-MsgGUID: XsbU4qmFRg6A46sIojj1Iw== X-IronPort-AV: E=McAfee;i="6700,10204,11275"; a="37236041" X-IronPort-AV: E=Sophos;i="6.12,205,1728975600"; d="scan'208";a="37236041" Received: from fmviesa007.fm.intel.com ([10.60.135.147]) by orvoesa106.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 03 Dec 2024 08:01:50 -0800 X-CSE-ConnectionGUID: 5NXC7kwaRM6M5bMoCnsxVg== X-CSE-MsgGUID: kNJWxcxaSvalCDKednLhpw== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.12,205,1728975600"; d="scan'208";a="93313031" Received: from ideak-desk.fi.intel.com ([10.237.72.78]) by fmviesa007-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 03 Dec 2024 08:01:45 -0800 From: Imre Deak To: intel-gfx@lists.freedesktop.org Cc: dri-devel@lists.freedesktop.org, Lyude Paul , stable@vger.kernel.org Subject: [PATCH 1/7] drm/dp_mst: Fix resetting msg rx state after topology removal Date: Tue, 3 Dec 2024 18:02:17 +0200 Message-ID: <20241203160223.2926014-2-imre.deak@intel.com> X-Mailer: git-send-email 2.44.2 In-Reply-To: <20241203160223.2926014-1-imre.deak@intel.com> References: <20241203160223.2926014-1-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 the MST topology is removed during the reception of an MST down reply or MST up request sideband message, the drm_dp_mst_topology_mgr::up_req_recv/down_rep_recv states could be reset from one thread via drm_dp_mst_topology_mgr_set_mst(false), racing with the reading/parsing of the message from another thread via drm_dp_mst_handle_down_rep() or drm_dp_mst_handle_up_req(). The race is possible since the reader/parser doesn't hold any lock while accessing the reception state. This in turn can lead to a memory corruption in the reader/parser as described by commit bd2fccac61b4 ("drm/dp_mst: Fix MST sideband message body length check"). Fix the above by resetting the message reception state if needed before reading/parsing a message. Another solution would be to hold the drm_dp_mst_topology_mgr::lock for the whole duration of the message reception/parsing in drm_dp_mst_handle_down_rep() and drm_dp_mst_handle_up_req(), however this would require a bigger change. Since the fix is also needed for stable, opting for the simpler solution in this patch. Cc: Lyude Paul Cc: Fixes: 1d082618bbf3 ("drm/display/dp_mst: Fix down/up message handling after sink disconnect") Closes: https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/13056 Signed-off-by: Imre Deak --- drivers/gpu/drm/display/drm_dp_mst_topology.c | 21 +++++++++++++++++-- include/drm/display/drm_dp_mst_helper.h | 7 +++++++ 2 files changed, 26 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/display/drm_dp_mst_topology.c b/drivers/gpu/drm/display/drm_dp_mst_topology.c index e6ee180815b20..1475aa95ab6b2 100644 --- a/drivers/gpu/drm/display/drm_dp_mst_topology.c +++ b/drivers/gpu/drm/display/drm_dp_mst_topology.c @@ -3700,8 +3700,7 @@ int drm_dp_mst_topology_mgr_set_mst(struct drm_dp_mst_topology_mgr *mgr, bool ms ret = 0; mgr->payload_id_table_cleared = false; - memset(&mgr->down_rep_recv, 0, sizeof(mgr->down_rep_recv)); - memset(&mgr->up_req_recv, 0, sizeof(mgr->up_req_recv)); + mgr->reset_rx_state = true; } out_unlock: @@ -3859,6 +3858,11 @@ int drm_dp_mst_topology_mgr_resume(struct drm_dp_mst_topology_mgr *mgr, } EXPORT_SYMBOL(drm_dp_mst_topology_mgr_resume); +static void reset_msg_rx_state(struct drm_dp_sideband_msg_rx *msg) +{ + memset(msg, 0, sizeof(*msg)); +} + static bool drm_dp_get_one_sb_msg(struct drm_dp_mst_topology_mgr *mgr, bool up, struct drm_dp_mst_branch **mstb) @@ -4141,6 +4145,17 @@ static int drm_dp_mst_handle_up_req(struct drm_dp_mst_topology_mgr *mgr) return 0; } +static void update_msg_rx_state(struct drm_dp_mst_topology_mgr *mgr) +{ + mutex_lock(&mgr->lock); + if (mgr->reset_rx_state) { + mgr->reset_rx_state = false; + reset_msg_rx_state(&mgr->down_rep_recv); + reset_msg_rx_state(&mgr->up_req_recv); + } + mutex_unlock(&mgr->lock); +} + /** * drm_dp_mst_hpd_irq_handle_event() - MST hotplug IRQ handle MST event * @mgr: manager to notify irq for. @@ -4175,6 +4190,8 @@ int drm_dp_mst_hpd_irq_handle_event(struct drm_dp_mst_topology_mgr *mgr, const u *handled = true; } + update_msg_rx_state(mgr); + if (esi[1] & DP_DOWN_REP_MSG_RDY) { ret = drm_dp_mst_handle_down_rep(mgr); *handled = true; diff --git a/include/drm/display/drm_dp_mst_helper.h b/include/drm/display/drm_dp_mst_helper.h index f6a1cbb0f600f..a80ba457a858f 100644 --- a/include/drm/display/drm_dp_mst_helper.h +++ b/include/drm/display/drm_dp_mst_helper.h @@ -699,6 +699,13 @@ struct drm_dp_mst_topology_mgr { */ bool payload_id_table_cleared : 1; + /** + * @reset_rx_state: The down request's reply and up request message + * receiver state must be reset, after the topology manager got + * removed. Protected by @lock. + */ + bool reset_rx_state : 1; + /** * @payload_count: The number of currently active payloads in hardware. This value is only * intended to be used internally by MST helpers for payload tracking, and is only safe to