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 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 B7BB8CD6E69 for ; Wed, 3 Jun 2026 09:39:30 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 185C710FADB; Wed, 3 Jun 2026 09:39:29 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=intel.com header.i=@intel.com header.b="ChgNY3wr"; dkim-atps=neutral Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.14]) by gabe.freedesktop.org (Postfix) with ESMTPS id 733C710FAD7; Wed, 3 Jun 2026 09:39:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1780479568; x=1812015568; h=from:to:cc:subject:in-reply-to:references:date: message-id:mime-version; bh=ai/Q0j191z64bA2k77aRNgjeIieXktAgLTqmnJOMi4Q=; b=ChgNY3wrr2Lb1re3QLd5iqFhPbuVOkpkWRiK8m3xqDCFBRXTIhGplXJ/ UyinniRwEjKHjW+8c8X6bgU2xxeQJzfk7S9ElOWM6pOlLPJhxBSWL8HGx HYb9v1FlEpVHmaRk2lEYG0MOqnZOXGOLHO2t/fBUxLC3dOylY6p1HxXlY zuRCStPQ6VnimV32vwTuPdBXZj7OxNpoTY7uDWQvxtxLakUcN6ZlGQQ+3 fklSEGVnEJspEefC9ocLGwx0HzH93jMFyPqFKbdxugMMa6fTqvz1DLV7X /qTRvMcHcrLlkX88dKY7YvtkholXDioV8RXe+aIxxsT7Q9aidTHdFG44k w==; X-CSE-ConnectionGUID: +f3jCFgVSieNDbfZiOMntQ== X-CSE-MsgGUID: vSdWeb4PTuOvQZCGQirY8w== X-IronPort-AV: E=McAfee;i="6800,10657,11805"; a="85168965" X-IronPort-AV: E=Sophos;i="6.24,184,1774335600"; d="scan'208";a="85168965" Received: from fmviesa007.fm.intel.com ([10.60.135.147]) by orvoesa106.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 03 Jun 2026 02:39:27 -0700 X-CSE-ConnectionGUID: thPgsvknT/2pjYKYcTbiOQ== X-CSE-MsgGUID: wpxLxYkFR0eajaXcSfab7A== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.24,184,1774335600"; d="scan'208";a="241182534" Received: from abityuts-desk.ger.corp.intel.com (HELO localhost) ([10.245.244.189]) by fmviesa007-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 03 Jun 2026 02:39:24 -0700 From: Jani Nikula To: Nikita Zhandarovich , Rodrigo Vivi , Joonas Lahtinen Cc: Nikita Zhandarovich , Tvrtko Ursulin , David Airlie , Simona Vetter , intel-gfx@lists.freedesktop.org, intel-xe@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, lvc-project@linuxtesting.org Subject: Re: [PATCH v2] drm/i915/edp: Check supported link rates DPCD read In-Reply-To: <824c6ced1095635f86527709822c8af3ddff7c8c@intel.com> Organization: Intel Finland Oy - BIC 0357606-4 - c/o Alberga Business Park, 6 krs Bertel Jungin Aukio 5, 02600 Espoo, Finland References: <20260529145759.1640646-1-n.zhandarovich@fintech.ru> <824c6ced1095635f86527709822c8af3ddff7c8c@intel.com> Date: Wed, 03 Jun 2026 12:39:21 +0300 Message-ID: <7b19689e97c8dc714d6dc28d0f92b0d6fd859c23@intel.com> MIME-Version: 1.0 Content-Type: text/plain 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" On Fri, 29 May 2026, Jani Nikula wrote: > On Fri, 29 May 2026, Nikita Zhandarovich wrote: >> intel_edp_set_sink_rates() reads DP_SUPPORTED_LINK_RATES into a local >> stack array and then parses the array unconditionally. If the read >> fails, the array contents are not valid and may result in bogus sink >> link rates being used. >> >> Use drm_dp_dpcd_read_data() and clear the sink rate array on failure, >> so the existing parser falls back to the default sink rate handling. >> >> Found by Linux Verification Center (linuxtesting.org) with static >> analysis tool SVACE. >> >> Fixes: 68f357cb7347 ("drm/i915/dp: generate and cache sink rate array for all DP, not just eDP 1.4") >> Signed-off-by: Nikita Zhandarovich > > Reviewed-by: Jani Nikula And pushed to drm-intel-next, thanks for the patch. > >> --- >> v1 -> v2: >> - Use drm_dp_dpcd_read_data() instead of drm_dp_dpcd_read(). >> - Avoid the goto by clearing sink_rates on read failure, as suggested by >> Jani Nikula. >> - Adjust patch description. >> >> drivers/gpu/drm/i915/display/intel_dp.c | 11 +++++++++-- >> 1 file changed, 9 insertions(+), 2 deletions(-) >> >> diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c >> index 6ef2a0043cda..5c3e816b0135 100644 >> --- a/drivers/gpu/drm/i915/display/intel_dp.c >> +++ b/drivers/gpu/drm/i915/display/intel_dp.c >> @@ -4678,10 +4678,17 @@ intel_edp_set_sink_rates(struct intel_dp *intel_dp) >> >> if (intel_dp->edp_dpcd[0] >= DP_EDP_14) { >> __le16 sink_rates[DP_MAX_SUPPORTED_RATES]; >> + int ret; >> int i; >> >> - drm_dp_dpcd_read(&intel_dp->aux, DP_SUPPORTED_LINK_RATES, >> - sink_rates, sizeof(sink_rates)); >> + ret = drm_dp_dpcd_read_data(&intel_dp->aux, >> + DP_SUPPORTED_LINK_RATES, >> + sink_rates, sizeof(sink_rates)); >> + if (ret < 0) { >> + drm_dbg_kms(display->drm, >> + "Unable to read eDP supported link rates, using default rates\n"); >> + memset(sink_rates, 0, sizeof(sink_rates)); >> + } >> >> for (i = 0; i < ARRAY_SIZE(sink_rates); i++) { >> int rate; -- Jani Nikula, Intel