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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 41C73C83F14 for ; Mon, 28 Aug 2023 11:17:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230029AbjH1LRQ (ORCPT ); Mon, 28 Aug 2023 07:17:16 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48966 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231140AbjH1LQ5 (ORCPT ); Mon, 28 Aug 2023 07:16:57 -0400 Received: from madras.collabora.co.uk (madras.collabora.co.uk [46.235.227.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F361B10E for ; Mon, 28 Aug 2023 04:16:52 -0700 (PDT) Received: from localhost (unknown [IPv6:2a01:e0a:2c:6930:5cf4:84a1:2763:fe0d]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) (Authenticated sender: bbrezillon) by madras.collabora.co.uk (Postfix) with ESMTPSA id D4F5F6600873; Mon, 28 Aug 2023 12:16:50 +0100 (BST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=collabora.com; s=mail; t=1693221411; bh=BlJFXTWexWp6mvkGqWMB8M7CVKV2UlUeerfJzGgXkj0=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=Liu0JclTWTa5GwqIj76KMimjJxucjirjetPeMy/4zi/a7zAYY4bZ3rgno8MzwEZzP U3CSKmxm5Cuh5UugQRoA9rE10Fl8VkICVV6Mh7BypkX1us9S2LaQKA9LPIfx5IkyPD /mIL+3xjmSy4cFgwXl9ckAVZ4DUzWJOG0WLA1+/kexc5NoPto0b14XIARubx8ljK59 OKYdqNFjnDhYYFy95JblbGvPDYTS+sL5EAfoCZyDUd5nTxTTbTeUQ5HoyXdOTt4Yzf c4Lj5EKxVLsHN5D8x0bx3uSxTFytFnMC3vvCvjqYkua/A3o6BkeK/l2c3OUc+0yqqY kPtPA5MfPbOaw== Date: Mon, 28 Aug 2023 13:16:47 +0200 From: Boris Brezillon To: Dmitry Osipenko Cc: David Airlie , Gerd Hoffmann , Gurchetan Singh , Chia-I Wu , Daniel Vetter , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , Christian =?UTF-8?B?S8O2bmln?= , Qiang Yu , Steven Price , Emma Anholt , Melissa Wen , Will Deacon , Peter Zijlstra , Boqun Feng , Mark Rutland , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, kernel@collabora.com, virtualization@lists.linux-foundation.org, intel-gfx@lists.freedesktop.org Subject: Re: [PATCH v15 01/23] drm/shmem-helper: Fix UAF in error path when freeing SGT of imported GEM Message-ID: <20230828131647.18888896@collabora.com> In-Reply-To: <20230827175449.1766701-2-dmitry.osipenko@collabora.com> References: <20230827175449.1766701-1-dmitry.osipenko@collabora.com> <20230827175449.1766701-2-dmitry.osipenko@collabora.com> Organization: Collabora X-Mailer: Claws Mail 4.1.1 (GTK 3.24.38; x86_64-redhat-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, 27 Aug 2023 20:54:27 +0300 Dmitry Osipenko wrote: > Freeing drm-shmem GEM right after creating it using > drm_gem_shmem_prime_import_sg_table() frees SGT of the imported dma-buf > and then dma-buf frees this SGT second time. > > The v3d_prime_import_sg_table() is example of a error code path where > dma-buf's SGT is freed by drm-shmem and then it's freed second time by > dma_buf_unmap_attachment() in drm_gem_prime_import_dev(). > > Add drm-shmem GEM flag telling that this is imported SGT shall not be > treated as own SGT, fixing the use-after-free bug. > > Cc: stable@vger.kernel.org > Fixes: 2194a63a818d ("drm: Add library for shmem backed GEM objects") > Signed-off-by: Dmitry Osipenko > --- > drivers/gpu/drm/drm_gem_shmem_helper.c | 3 ++- > include/drm/drm_gem_shmem_helper.h | 7 +++++++ > 2 files changed, 9 insertions(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c > index a783d2245599..78d9cf2355a5 100644 > --- a/drivers/gpu/drm/drm_gem_shmem_helper.c > +++ b/drivers/gpu/drm/drm_gem_shmem_helper.c > @@ -141,7 +141,7 @@ void drm_gem_shmem_free(struct drm_gem_shmem_object *shmem) > > if (obj->import_attach) { > drm_prime_gem_destroy(obj, shmem->sgt); > - } else { > + } else if (!shmem->imported_sgt) { > dma_resv_lock(shmem->base.resv, NULL); > > drm_WARN_ON(obj->dev, shmem->vmap_use_count); > @@ -758,6 +758,7 @@ drm_gem_shmem_prime_import_sg_table(struct drm_device *dev, > return ERR_CAST(shmem); > > shmem->sgt = sgt; > + shmem->imported_sgt = true; I feel like adding more fields that can be used to do the is_imported() check is going to be even more confusing. Can we instead have /* drm_gem_shmem_prime_import_sg_table() can be called from a * driver specific ->import_sg_table() implementations that * have extra failable initialization steps. Assign * drm_gem_object::import_attach here (even though it's * assigned in drm_gem_prime_import_dev()), so we don't end up * with driver error paths calling drm_gem_shmem_free() with an * imported sg_table assigned to drm_gem_shmem_object::sgt and * drm_gem_object::import_attach left uninitialized. */ shmem->base.import_attach = attach; here? > > drm_dbg_prime(dev, "size = %zu\n", size); > > diff --git a/include/drm/drm_gem_shmem_helper.h b/include/drm/drm_gem_shmem_helper.h > index bf0c31aa8fbe..ec70a98a8fe1 100644 > --- a/include/drm/drm_gem_shmem_helper.h > +++ b/include/drm/drm_gem_shmem_helper.h > @@ -73,6 +73,13 @@ struct drm_gem_shmem_object { > */ > unsigned int vmap_use_count; > > + /** > + * @imported_sgt: > + * > + * True if SG table belongs to imported dma-buf. > + */ > + bool imported_sgt : 1; > + > /** > * @pages_mark_dirty_on_put: > *