From nobody Thu May 2 01:37:35 2024 Delivered-To: importer@patchew.org Received-SPF: pass (zoho.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; Authentication-Results: mx.zohomail.com; spf=pass (zoho.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=fail(p=none dis=none) header.from=intel.com Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1552388523837742.4232624538614; Tue, 12 Mar 2019 04:02:03 -0700 (PDT) Received: from localhost ([127.0.0.1]:49800 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1h3fAW-0007Gz-If for importer@patchew.org; Tue, 12 Mar 2019 07:02:00 -0400 Received: from eggs.gnu.org ([209.51.188.92]:40117) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1h3eNO-00019e-46 for qemu-devel@nongnu.org; Tue, 12 Mar 2019 06:11:15 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1h3eNN-0001Qo-5Z for qemu-devel@nongnu.org; Tue, 12 Mar 2019 06:11:14 -0400 Received: from mga18.intel.com ([134.134.136.126]:12745) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1h3eNM-0001Mn-SG for qemu-devel@nongnu.org; Tue, 12 Mar 2019 06:11:13 -0400 Received: from orsmga001.jf.intel.com ([10.7.209.18]) by orsmga106.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 12 Mar 2019 03:11:08 -0700 Received: from devel-ww.sh.intel.com ([10.239.48.128]) by orsmga001.jf.intel.com with ESMTP; 12 Mar 2019 03:11:07 -0700 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.58,470,1544515200"; d="scan'208";a="208461511" From: Wei Wang To: qemu-devel@nongnu.org, virtio-dev@lists.oasis-open.org, mst@redhat.com, quintela@redhat.com, dgilbert@redhat.com, peterx@redhat.com Date: Tue, 12 Mar 2019 17:34:40 +0800 Message-Id: <1552383280-4122-1-git-send-email-wei.w.wang@intel.com> X-Mailer: git-send-email 2.7.4 X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 134.134.136.126 Subject: [Qemu-devel] [PATCH] virtio-balloon: fix a use-after-free case X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: peter.maydell@linaro.org Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" The elem could theorically contain both outbuf and inbufs. We move the free operation to the end of this function to avoid using elem->in_sg while elem has been freed. Fixes: c13c4153f7 ("virtio-balloon: VIRTIO_BALLOON_F_FREE_PAGE_HINT") Reported-by: Peter Maydell Signed-off-by: Wei Wang CC: Michael S. Tsirkin CC: Dr. David Alan Gilbert CC: Juan Quintela CC: Peter Xu --- hw/virtio/virtio-balloon.c | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-) diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c index e3a6594..b614552 100644 --- a/hw/virtio/virtio-balloon.c +++ b/hw/virtio/virtio-balloon.c @@ -391,6 +391,7 @@ static bool get_free_page_hints(VirtIOBalloon *dev) VirtQueueElement *elem; VirtIODevice *vdev =3D VIRTIO_DEVICE(dev); VirtQueue *vq =3D dev->free_page_vq; + bool ret =3D true; =20 while (dev->block_iothread) { qemu_cond_wait(&dev->free_page_cond, &dev->free_page_lock); @@ -405,13 +406,12 @@ static bool get_free_page_hints(VirtIOBalloon *dev) uint32_t id; size_t size =3D iov_to_buf(elem->out_sg, elem->out_num, 0, &id, sizeof(id)); - virtqueue_push(vq, elem, size); - g_free(elem); =20 virtio_tswap32s(vdev, &id); if (unlikely(size !=3D sizeof(id))) { virtio_error(vdev, "received an incorrect cmd id"); - return false; + ret =3D false; + goto out; } if (id =3D=3D dev->free_page_report_cmd_id) { dev->free_page_report_status =3D FREE_PAGE_REPORT_S_START; @@ -431,11 +431,12 @@ static bool get_free_page_hints(VirtIOBalloon *dev) qemu_guest_free_page_hint(elem->in_sg[0].iov_base, elem->in_sg[0].iov_len); } - virtqueue_push(vq, elem, 1); - g_free(elem); } =20 - return true; +out: + virtqueue_push(vq, elem, 1); + g_free(elem); + return ret; } =20 static void virtio_ballloon_get_free_page_hints(void *opaque) --=20 1.8.3.1