Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754617AbbBQC2K (ORCPT ); Mon, 16 Feb 2015 21:28:10 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:33803 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752040AbbBQBu6 (ORCPT ); Mon, 16 Feb 2015 20:50:58 -0500 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Michael S. Tsirkin" , "Sasha Levin" Date: Tue, 17 Feb 2015 01:46:53 +0000 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.2 083/152] virtio_pci: defer kfree until release callback In-Reply-To: X-SA-Exim-Connect-IP: 192.168.4.249 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2168 Lines: 66 3.2.67-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Sasha Levin commit 63bd62a08ca45a0c804c3c89777edc7f76a2d6da upstream. A struct device which has just been unregistered can live on past the point at which a driver decides to drop it's initial reference to the kobject gained on allocation. This implies that when releasing a virtio device, we can't free a struct virtio_device until the underlying struct device has been released, which might not happen immediately on device_unregister(). Unfortunately, this is exactly what virtio pci does: it has an empty release callback, and frees memory immediately after unregistering the device. This causes an easy to reproduce crash if CONFIG_DEBUG_KOBJECT_RELEASE it enabled. To fix, free the memory only once we know the device is gone in the release callback. Signed-off-by: Sasha Levin Signed-off-by: Michael S. Tsirkin [bwh: Backported to 3.2: adjust filename] Signed-off-by: Ben Hutchings --- drivers/virtio/virtio_pci.c | 10 ++++------ 1 file changed, 4 insertions(+), 6 deletions(-) --- a/drivers/virtio/virtio_pci.c +++ b/drivers/virtio/virtio_pci.c @@ -612,11 +612,10 @@ static struct virtio_config_ops virtio_p static void virtio_pci_release_dev(struct device *_d) { - /* - * No need for a release method as we allocate/free - * all devices together with the pci devices. - * Provide an empty one to avoid getting a warning from core. - */ + struct virtio_device *vdev = dev_to_virtio(_d); + struct virtio_pci_device *vp_dev = to_vp_device(vdev); + + kfree(vp_dev); } /* the PCI probing function */ @@ -704,7 +703,6 @@ static void __devexit virtio_pci_remove( pci_iounmap(pci_dev, vp_dev->ioaddr); pci_release_regions(pci_dev); pci_disable_device(pci_dev); - kfree(vp_dev); } #ifdef CONFIG_PM -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/