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 9E70DC433FE for ; Wed, 26 Oct 2022 11:24:35 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 3AE3810E4A7; Wed, 26 Oct 2022 11:24:34 +0000 (UTC) Received: from madras.collabora.co.uk (madras.collabora.co.uk [46.235.227.172]) by gabe.freedesktop.org (Postfix) with ESMTPS id 5DBC610E4A7 for ; Wed, 26 Oct 2022 11:24:30 +0000 (UTC) Received: from [192.168.2.190] (109-252-112-196.nat.spd-mgts.ru [109.252.112.196]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) (Authenticated sender: dmitry.osipenko) by madras.collabora.co.uk (Postfix) with ESMTPSA id C977E6602534; Wed, 26 Oct 2022 12:24:26 +0100 (BST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=collabora.com; s=mail; t=1666783467; bh=lCFwG51qgOU7nP/LILNhxiwyDR4ncmY4dkzi9tBswKo=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=cIAOxZGvT1YJAYDEvRQb19BsPgj6XPI1pd+Dnh8eKuQgEzeCUe8ZUh7n4eNOqL1Yr wZN4GwbZ8qP9lYBT8HLwLl+Ti1IZrXh6sNajhyjtFTpymkFAUoQ8TPA9/+3NONB0Nq qbC2EqZKTBCdK0qUKmdqNFD0Y+UZBWwm88FB8oXyivVNDy0g+emjGpREdXA7LNEVOZ kMNdQ8RxiGmPlrq4jRPCRu99GY0klwgd2PmcoG4r+g4N8uhYOoHuHDE+wAD8PV42Fi 3Jn0kaUWkZKh/Db5hEms4Y83L3ZNHhmhiWm0kul+Auc6ZZk2MjFbT4KWmcbcLO94wW vW9kEm4v6cqug== Message-ID: <514fa15a-b039-2f84-1be8-b881fee72235@collabora.com> Date: Wed, 26 Oct 2022 14:24:23 +0300 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.3.1 Subject: Re: [bug report] drm/gem: Add drm_gem_object_funcs To: Dan Carpenter , noralf@tronnes.org References: Content-Language: en-US From: Dmitry Osipenko In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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: , Cc: dri-devel@lists.freedesktop.org Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" On 10/26/22 12:59, Dan Carpenter wrote: > Hello Noralf Trønnes, > > The patch b39b5394fabc: "drm/gem: Add drm_gem_object_funcs" from Nov > 10, 2018, leads to the following Smatch static checker warning: > > drivers/gpu/drm/drm_client.c:240 drm_client_buffer_delete() > warn: variable dereferenced before check 'buffer->gem' (see line 238) > > drivers/gpu/drm/drm_client.c > 234 static void drm_client_buffer_delete(struct drm_client_buffer *buffer) > 235 { > 236 struct drm_device *dev = buffer->client->dev; > 237 > 238 drm_gem_vunmap_unlocked(buffer->gem, &buffer->map); > ^^^^^^^^^^^ > Unchecked dereference inside function call. > > 239 > --> 240 if (buffer->gem) > ^^^^^^^^^^^ > Too late. I don't honestly, know why this warning is only showing up > now four years later. Perhaps Smatch thought buffer->gem was always > non-NULL before but now it's not sure. I've added Dmitry to the CC list > because he seems to has been working in this area recently and might > know what's going on. This is a valid bug. Before my changes drm_gem_vunmap() wasn't touching buffer->gem when buffer->map=NULL, now it will. I'll prepare the fix, thank you for the report. -- Best regards, Dmitry