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=-9.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,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 6174BC43381 for ; Tue, 26 Feb 2019 20:49:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2177A21850 for ; Tue, 26 Feb 2019 20:49:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1551214179; bh=VS8jlFSPrAR/4fBl2zpXd+tqA6b2F0cLVXZ7ij6dvmg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=XexisomIudMNW8qL1VZNtXsRCgS8p8PDqipu/ziVUnWQrC8ojSVnc6bKr7YHNUC9S hvv5cmytKctOlL1e0IqrH3leWO0ljz8Dcs9ztDQmgYo906c3lFFYaz7jQu/oF0cVL7 ma+DTD+BTiGreGHt+8BLFe9p1WWoKX10kkLYrZpU= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729101AbfBZUth (ORCPT ); Tue, 26 Feb 2019 15:49:37 -0500 Received: from mail.kernel.org ([198.145.29.99]:37408 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727823AbfBZUth (ORCPT ); Tue, 26 Feb 2019 15:49:37 -0500 Received: from ebiggers-linuxstation.mtv.corp.google.com (unknown [104.132.1.77]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 4BC3E21873; Tue, 26 Feb 2019 20:49:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1551214176; bh=VS8jlFSPrAR/4fBl2zpXd+tqA6b2F0cLVXZ7ij6dvmg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=UIOeve8JiDVxwY3B7KducRsC6ZVAShyagQlxBnB339u/4l5bsfdU1ToxNQuVAXsqg 4/ZTDZkngbNLlszhpSeYCZfwNNuLxnKVmSGOlMJg1NuR9IdBHRrgA36QVRKt+qAVqq 6N5I200ZeRGMzOc0zBxrM4w2g+W8ErAEdoqtrn8w= From: Eric Biggers To: dri-devel@lists.freedesktop.org, David Airlie , Daniel Vetter Cc: Chris Wilson , syzkaller-bugs , linux-kernel@vger.kernel.org Subject: [PATCH] drm/vgem: fix use-after-free when drm_gem_handle_create() fails Date: Tue, 26 Feb 2019 12:47:26 -0800 Message-Id: <20190226204726.92256-1-ebiggers@kernel.org> X-Mailer: git-send-email 2.21.0.rc2.261.ga7da99ff1b-goog In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Eric Biggers If drm_gem_handle_create() fails in vgem_gem_create(), then the drm_vgem_gem_object is freed twice: once when the reference is dropped by drm_gem_object_put_unlocked(), and again by __vgem_gem_destroy(). This was hit by syzkaller using fault injection. Fix it by skipping the second free. Reported-by: syzbot+e73f2fb5ed5a5df36d33@syzkaller.appspotmail.com Fixes: 5ba6c9ff961a ("drm/vgem: Fix mmaping") Cc: stable@vger.kernel.org Signed-off-by: Eric Biggers --- drivers/gpu/drm/vgem/vgem_drv.c | 8 +++----- 1 file changed, 3 insertions(+), 5 deletions(-) diff --git a/drivers/gpu/drm/vgem/vgem_drv.c b/drivers/gpu/drm/vgem/vgem_drv.c index 5930facd6d2d8..70646d9da1596 100644 --- a/drivers/gpu/drm/vgem/vgem_drv.c +++ b/drivers/gpu/drm/vgem/vgem_drv.c @@ -189,15 +189,13 @@ static struct drm_gem_object *vgem_gem_create(struct drm_device *dev, return ERR_CAST(obj); ret = drm_gem_handle_create(file, &obj->base, handle); + drm_gem_object_put_unlocked(&obj->base); + if (ret) - goto err; + return ERR_PTR(ret); return &obj->base; - -err: - __vgem_gem_destroy(obj); - return ERR_PTR(ret); } static int vgem_gem_dumb_create(struct drm_file *file, struct drm_device *dev, -- 2.21.0.rc2.261.ga7da99ff1b-goog