From patchwork Mon Apr 19 13:05:07 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 425247 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=-18.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED, USER_AGENT_GIT autolearn=ham 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 F04C6C43461 for ; Mon, 19 Apr 2021 13:10:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C0ADB613CA for ; Mon, 19 Apr 2021 13:10:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239799AbhDSNKq (ORCPT ); Mon, 19 Apr 2021 09:10:46 -0400 Received: from mail.kernel.org ([198.145.29.99]:45730 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239543AbhDSNKT (ORCPT ); Mon, 19 Apr 2021 09:10:19 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 9F30561364; Mon, 19 Apr 2021 13:09:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1618837789; bh=W3iOE/Wa3LsOIi6d8vM+vpVkXrlNqypmWBEd7yr3rhA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=tR/SF3Ql15DQFS66TieHetkpCBpOe5HHHQoeHSPpgw+zK7VP49EKBKXPoyR4LFW5M 1/LJuw1HK1mXmhpmdFXqhmkudjEHqy9YDejgzr3ZvkC3dI1WB+N8f5+XbVUM3zpKOl kIkoCT2bkN6LWd828k/U1gpMj1Upvji0eTkx0NxQ= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Lv Yunlong , Oleksandr Andrushchenko , Sasha Levin Subject: [PATCH 5.11 027/122] gpu/xen: Fix a use after free in xen_drm_drv_init Date: Mon, 19 Apr 2021 15:05:07 +0200 Message-Id: <20210419130531.088507115@linuxfoundation.org> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210419130530.166331793@linuxfoundation.org> References: <20210419130530.166331793@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Lv Yunlong [ Upstream commit 52762efa2b256ed1c5274e5177cbd52ee11a2f6a ] In function displback_changed, has the call chain displback_connect(front_info)->xen_drm_drv_init(front_info). We can see that drm_info is assigned to front_info->drm_info and drm_info is freed in fail branch in xen_drm_drv_init(). Later displback_disconnect(front_info) is called and it calls xen_drm_drv_fini(front_info) cause a use after free by drm_info = front_info->drm_info statement. My patch has done two things. First fixes the fail label which drm_info = kzalloc() failed and still free the drm_info. Second sets front_info->drm_info to NULL to avoid uaf. Signed-off-by: Lv Yunlong Reviewed-by: Oleksandr Andrushchenko Signed-off-by: Oleksandr Andrushchenko Link: https://patchwork.freedesktop.org/patch/msgid/20210323014656.10068-1-lyl2019@mail.ustc.edu.cn Signed-off-by: Sasha Levin --- drivers/gpu/drm/xen/xen_drm_front.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/xen/xen_drm_front.c b/drivers/gpu/drm/xen/xen_drm_front.c index 30d9adf31c84..9f14d99c763c 100644 --- a/drivers/gpu/drm/xen/xen_drm_front.c +++ b/drivers/gpu/drm/xen/xen_drm_front.c @@ -521,7 +521,7 @@ static int xen_drm_drv_init(struct xen_drm_front_info *front_info) drm_dev = drm_dev_alloc(&xen_drm_driver, dev); if (IS_ERR(drm_dev)) { ret = PTR_ERR(drm_dev); - goto fail; + goto fail_dev; } drm_info->drm_dev = drm_dev; @@ -551,8 +551,10 @@ fail_modeset: drm_kms_helper_poll_fini(drm_dev); drm_mode_config_cleanup(drm_dev); drm_dev_put(drm_dev); -fail: +fail_dev: kfree(drm_info); + front_info->drm_info = NULL; +fail: return ret; }