Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752054AbdIUOcU (ORCPT ); Thu, 21 Sep 2017 10:32:20 -0400 Received: from mga09.intel.com ([134.134.136.24]:10530 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751909AbdIUOcR (ORCPT ); Thu, 21 Sep 2017 10:32:17 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.42,425,1500966000"; d="scan'208";a="153964438" Message-ID: <1506004318.5382.4.camel@linux.intel.com> Subject: Re: [PATCH][drm-next] drm/i915/gvt: ensure -ve return value is handled correctly From: Joonas Lahtinen To: Zhenyu Wang , Joe Perches Cc: Colin King , fred gao , Zhi Wang , Jani Nikula , Rodrigo Vivi , David Airlie , intel-gvt-dev@lists.freedesktop.org, intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, kernel-janitors@vger.kernel.org, linux-kernel@vger.kernel.org Date: Thu, 21 Sep 2017 17:31:58 +0300 In-Reply-To: <20170920224406.jscthkglwfy3xhtf@zhen-hp.sh.intel.com> References: <20170919155534.25334-1-colin.king@canonical.com> <20170919214614.cfiolgznopouv34e@zhen-hp.sh.intel.com> <1505874923.2067.14.camel@perches.com> <20170920224406.jscthkglwfy3xhtf@zhen-hp.sh.intel.com> Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.24.5 (3.24.5-1.fc26) Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2128 Lines: 52 On Thu, 2017-09-21 at 06:44 +0800, Zhenyu Wang wrote: > On 2017.09.19 19:35:23 -0700, Joe Perches wrote: > > On Wed, 2017-09-20 at 05:46 +0800, Zhenyu Wang wrote: > > > On 2017.09.19 16:55:34 +0100, Colin King wrote: > > > > From: Colin Ian King > > > > > > > > An earlier fix changed the return type from find_bb_size however the > > > > integer return is being assigned to a unsigned int so the -ve error > > > > check will never be detected. Make bb_size an int to fix this. > > > > > > > > Detected by CoverityScan CID#1456886 ("Unsigned compared against 0") > > > > > > > > Fixes: 1e3197d6ad73 ("drm/i915/gvt: Refine error handling for perform_bb_shadow") > > > > Signed-off-by: Colin Ian King > > > > --- > > > > drivers/gpu/drm/i915/gvt/cmd_parser.c | 2 +- > > > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > > > > > diff --git a/drivers/gpu/drm/i915/gvt/cmd_parser.c b/drivers/gpu/drm/i915/gvt/cmd_parser.c > > > > index 2c0ccbb817dc..f41cbf664b69 100644 > > > > --- a/drivers/gpu/drm/i915/gvt/cmd_parser.c > > > > +++ b/drivers/gpu/drm/i915/gvt/cmd_parser.c > > > > @@ -1628,7 +1628,7 @@ static int perform_bb_shadow(struct parser_exec_state *s) > > > > struct intel_shadow_bb_entry *entry_obj; > > > > struct intel_vgpu *vgpu = s->vgpu; > > > > unsigned long gma = 0; > > > > - uint32_t bb_size; > > > > + int bb_size; > > > > void *dst = NULL; > > > > int ret = 0; > > > > > > > > > > Applied this, thanks! > > > > Is it possible for bb_size to be both >= 2g and valid? > > Never be possible in practise and if really that big I think something > is already insane indeed. It's good idea to document these assumptions as WARN_ON's. In i915, if the value is completely internal to kernel, we're using GEM_BUG_ON for these so that our CI will notice breakage. If it's not a driver internal value only, a WARN_ON is the appropriate action. Otherwise the information is lost and the next person reading the code will have the same question in mind. Regards, Joonas -- Joonas Lahtinen Open Source Technology Center Intel Corporation