From nobody Wed Feb 11 04:02:49 2026 Delivered-To: importer@patchew.org Authentication-Results: mx.zohomail.com; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1770726279510471.69501891051505; Tue, 10 Feb 2026 04:24:39 -0800 (PST) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1vpmif-00005z-0Y; Tue, 10 Feb 2026 07:19:53 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1vpmgq-0005Bn-PU; Tue, 10 Feb 2026 07:18:01 -0500 Received: from isrv.corpit.ru ([212.248.84.144]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1vpmgo-00016v-R1; Tue, 10 Feb 2026 07:18:00 -0500 Received: from tsrv.corpit.ru (tsrv.tls.msk.ru [192.168.177.2]) by isrv.corpit.ru (Postfix) with ESMTP id 3B889187DC1; Tue, 10 Feb 2026 15:14:47 +0300 (MSK) Received: from think4mjt.tls.msk.ru (mjtthink.wg.tls.msk.ru [192.168.177.146]) by tsrv.corpit.ru (Postfix) with ESMTP id CC891360CE6; Tue, 10 Feb 2026 15:15:42 +0300 (MSK) From: Michael Tokarev To: qemu-devel@nongnu.org Cc: qemu-stable@nongnu.org, Joelle van Dyne , Akihiko Odaki , "Michael S. Tsirkin" , Michael Tokarev Subject: [Stable-10.1.4 89/95] virtio-gpu-virgl: correct parent for blob memory region Date: Tue, 10 Feb 2026 15:15:11 +0300 Message-ID: <20260210121526.68598-15-mjt@tls.msk.ru> X-Mailer: git-send-email 2.47.3 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=212.248.84.144; envelope-from=mjt@tls.msk.ru; helo=isrv.corpit.ru X-Spam_score_int: -18 X-Spam_score: -1.9 X-Spam_bar: - X-Spam_report: (-1.9 / 5.0 requ) BAYES_00=-1.9, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: qemu development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZM-MESSAGEID: 1770726281438154100 Content-Type: text/plain; charset="utf-8" From: Joelle van Dyne When `owner` =3D=3D `mr`, `object_unparent` will crash: object_unparent(mr) -> object_property_del_child(mr, mr) -> object_finalize_child_property(mr, name, mr) -> object_unref(mr) -> object_finalize(mr) -> object_property_del_all(mr) -> object_finalize_child_property(mr, name, mr) -> object_unref(mr) -> fail on g_assert(obj->ref > 0) However, passing a different `owner` to `memory_region_init` does not work. `memory_region_ref` has an optimization where it takes a ref only on the owner. That means when flatviews are created, it does not take a ref on the region and you can get a UAF from `flatview_destroy` called from RCU. The correct fix therefore is to use `NULL` as the name which will set the `owner` but not the `parent` (which is still NULL). This allows us to use `memory_region_ref` on itself while not having to rely on unparent for cleanup. Signed-off-by: Joelle van Dyne Reviewed-by: Akihiko Odaki Reviewed-by: Michael S. Tsirkin Signed-off-by: Michael S. Tsirkin Message-Id: <20260103214400.71694-1-j@getutm.app> (cherry picked from commit e27194e087aede62dbe3d2805c6f1aa30d3465df) Signed-off-by: Michael Tokarev diff --git a/hw/display/virtio-gpu-virgl.c b/hw/display/virtio-gpu-virgl.c index 94ddc01f91..ca34704acb 100644 --- a/hw/display/virtio-gpu-virgl.c +++ b/hw/display/virtio-gpu-virgl.c @@ -120,7 +120,7 @@ virtio_gpu_virgl_map_resource_blob(VirtIOGPU *g, vmr->g =3D g; =20 mr =3D &vmr->mr; - memory_region_init_ram_ptr(mr, OBJECT(mr), "blob", size, data); + memory_region_init_ram_ptr(mr, OBJECT(mr), NULL, size, data); memory_region_add_subregion(&b->hostmem, offset, mr); memory_region_set_enabled(mr, true); =20 @@ -182,7 +182,7 @@ virtio_gpu_virgl_unmap_resource_blob(VirtIOGPU *g, /* memory region owns self res->mr object and frees it by itself */ memory_region_set_enabled(mr, false); memory_region_del_subregion(&b->hostmem, mr); - object_unparent(OBJECT(mr)); + object_unref(OBJECT(mr)); } =20 return 0; --=20 2.47.3