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 X-Spam-Level: X-Spam-Status: No, score=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6A4FDC4338F for ; Wed, 18 Aug 2021 07:40:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 48C31606A5 for ; Wed, 18 Aug 2021 07:40:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239229AbhHRHlS (ORCPT ); Wed, 18 Aug 2021 03:41:18 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38006 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239245AbhHRHlM (ORCPT ); Wed, 18 Aug 2021 03:41:12 -0400 Received: from mail-pl1-x630.google.com (mail-pl1-x630.google.com [IPv6:2607:f8b0:4864:20::630]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3D911C061796; Wed, 18 Aug 2021 00:40:38 -0700 (PDT) Received: by mail-pl1-x630.google.com with SMTP id o10so1327142plg.0; Wed, 18 Aug 2021 00:40:38 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=he3hjgMVhcOXzxQ8ZzPKGe5qy8qOVQuZUYfKXwOfAPg=; b=V3ChonAMDLG13W4R9mt1UZfcDRlf3NYYG5Rp6zwLe9hoPv7kNaLSz1SBaGSu4gacb2 IG7pihFofk738zo0sUjjMECc8BKbXHoRFgXUaz+rksmgG1umJdIhslaO4DouScE25nrz QhQN0KBGfOlxOAV5gm+r9YxMmPtBF13v/W8YFP2iCl19RlJ5zdD+L2hOm2sa+1iKHZGz CgFFYbvwQ/FegyZK22MDmuuW+iQHHAazsx4WnIW9u2x3s0WyVCRHOYH7otiYZitptlk3 7J02sZUKJx/5shMUykUIDn5WogVBsFWvX2MIVtWcImlFFB8LyqmG2vbSKdj3J6amSb+W /hSg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=he3hjgMVhcOXzxQ8ZzPKGe5qy8qOVQuZUYfKXwOfAPg=; b=YBXT09Z4Mm9MZxnPeLB53s6OMQFtI4qCWuuEQTx5ZdV/0kTADHqdeiPwsZcDyA7nk0 ej4+VNkKbgm9SzfQoIpRcQVAs0MW+VKHu7MUVpunVxU2/EUGpvbj9zbOW/TpiFCTFF5x hFtDIfAYc6TfbaDTJ2YO1oUyTSzW/CYula56SoKCIQZxQ+LRN/ITWQfDz2Ov26O+Wz5Y JqkmhbqE1ZezoGLqjm8oLWBYKiGEuDP5cVLJkpqDmB2HkQsTHgPp1sgplbbhHhG4WYOz BjfWenJVPyKCoxV3qliqtS9QlrrTq8Xigw6dSB448r6h5Pj1GRjSC1OZZPxndbuwj1kN kPGA== X-Gm-Message-State: AOAM531GLsxjwe9JoD/VPUAOj+REPbmkdvMp9N6kfEgWYvzS8vHKNI3x 3irW24mvyEMRqtcVBL2WlwA= X-Google-Smtp-Source: ABdhPJykotiJspllqjLdDweoNoswYBNnKnCEjOlyfwnrSucYaBkYPe1fsbb0KtPlQEnYeO0NwCNLag== X-Received: by 2002:a17:90a:b009:: with SMTP id x9mr7893927pjq.97.1629272437819; Wed, 18 Aug 2021 00:40:37 -0700 (PDT) Received: from localhost.localdomain ([118.200.190.93]) by smtp.gmail.com with ESMTPSA id u3sm3886729pjr.2.2021.08.18.00.40.32 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 18 Aug 2021 00:40:37 -0700 (PDT) From: Desmond Cheong Zhi Xi To: maarten.lankhorst@linux.intel.com, mripard@kernel.org, tzimmermann@suse.de, airlied@linux.ie, daniel@ffwll.ch, sumit.semwal@linaro.org, christian.koenig@amd.com, axboe@kernel.dk, oleg@redhat.com, tglx@linutronix.de, dvyukov@google.com, walter-zh.wu@mediatek.com Cc: Desmond Cheong Zhi Xi , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, intel-gfx@lists.freedesktop.org, linux-media@vger.kernel.org, linaro-mm-sig@lists.linaro.org, skhan@linuxfoundation.org, gregkh@linuxfoundation.org, linux-kernel-mentees@lists.linuxfoundation.org Subject: [PATCH v3 3/9] drm: check for null master in drm_is_current_master_locked Date: Wed, 18 Aug 2021 15:38:18 +0800 Message-Id: <20210818073824.1560124-4-desmondcheongzx@gmail.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20210818073824.1560124-1-desmondcheongzx@gmail.com> References: <20210818073824.1560124-1-desmondcheongzx@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org There is a window after calling drm_master_release, and before a file is freed, where drm_file can have is_master set to true, but both the drm_file and drm_device have no master. This could result in wrongly approving permissions in drm_is_current_master_locked. Add a check that fpriv->master is non-NULl to guard against this scenario. Signed-off-by: Desmond Cheong Zhi Xi --- drivers/gpu/drm/drm_auth.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/drm_auth.c b/drivers/gpu/drm/drm_auth.c index 8c0e0dba1611..f9267b21556e 100644 --- a/drivers/gpu/drm/drm_auth.c +++ b/drivers/gpu/drm/drm_auth.c @@ -66,7 +66,8 @@ static bool drm_is_current_master_locked(struct drm_file *fpriv) lockdep_assert_once(lockdep_is_held(&fpriv->minor->dev->master_lookup_lock) || lockdep_is_held(&fpriv->minor->dev->master_mutex)); - return fpriv->is_master && drm_lease_owner(fpriv->master) == fpriv->minor->dev->master; + return (fpriv->is_master && fpriv->master && + drm_lease_owner(fpriv->master) == fpriv->minor->dev->master); } /** -- 2.25.1