Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932527AbdCFWWg (ORCPT ); Mon, 6 Mar 2017 17:22:36 -0500 Received: from mail.kernel.org ([198.145.29.136]:40754 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754084AbdCFWVc (ORCPT ); Mon, 6 Mar 2017 17:21:32 -0500 Date: Mon, 6 Mar 2017 15:38:29 -0600 From: Bjorn Helgaas To: Elena Reshetova Cc: linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, Hans Liljestrand , Kees Cook , David Windsor , "K. Y. Srinivasan" , Haiyang Zhang , Stephen Hemminger , devel@linuxdriverproject.org Subject: Re: [PATCH 17/29] drivers, pci: convert hv_pci_dev.refs from atomic_t to refcount_t Message-ID: <20170306213829.GB5305@bhelgaas-glaptop.roam.corp.google.com> References: <1488810076-3754-1-git-send-email-elena.reshetova@intel.com> <1488810076-3754-18-git-send-email-elena.reshetova@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1488810076-3754-18-git-send-email-elena.reshetova@intel.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2250 Lines: 66 [+cc Hyper-V folks, -cc others] On Mon, Mar 06, 2017 at 04:21:04PM +0200, Elena Reshetova wrote: > refcount_t type and corresponding API should be > used instead of atomic_t when the variable is used as > a reference counter. This allows to avoid accidental > refcounter overflows that might lead to use-after-free > situations. > > Signed-off-by: Elena Reshetova > Signed-off-by: Hans Liljestrand > Signed-off-by: Kees Cook > Signed-off-by: David Windsor > --- > drivers/pci/host/pci-hyperv.c | 9 +++++---- > 1 file changed, 5 insertions(+), 4 deletions(-) > > diff --git a/drivers/pci/host/pci-hyperv.c b/drivers/pci/host/pci-hyperv.c > index cd114c6..870deed 100644 > --- a/drivers/pci/host/pci-hyperv.c > +++ b/drivers/pci/host/pci-hyperv.c > @@ -56,6 +56,7 @@ > #include > #include > #include > +#include > #include > > /* > @@ -421,7 +422,7 @@ enum hv_pcidev_ref_reason { > struct hv_pci_dev { > /* List protected by pci_rescan_remove_lock */ > struct list_head list_entry; > - atomic_t refs; > + refcount_t refs; > enum hv_pcichild_state state; > struct pci_function_description desc; > bool reported_missing; > @@ -1254,13 +1255,13 @@ static void q_resource_requirements(void *context, struct pci_response *resp, > static void get_pcichild(struct hv_pci_dev *hpdev, > enum hv_pcidev_ref_reason reason) > { > - atomic_inc(&hpdev->refs); > + refcount_inc(&hpdev->refs); > } > > static void put_pcichild(struct hv_pci_dev *hpdev, > enum hv_pcidev_ref_reason reason) > { > - if (atomic_dec_and_test(&hpdev->refs)) > + if (refcount_dec_and_test(&hpdev->refs)) > kfree(hpdev); > } > > @@ -1314,7 +1315,7 @@ static struct hv_pci_dev *new_pcichild_device(struct hv_pcibus_device *hbus, > wait_for_completion(&comp_pkt.host_event); > > hpdev->desc = *desc; > - get_pcichild(hpdev, hv_pcidev_ref_initial); > + refcount_set(&hpdev->refs, 1); > get_pcichild(hpdev, hv_pcidev_ref_childlist); > spin_lock_irqsave(&hbus->device_list_lock, flags); > list_add_tail(&hpdev->list_entry, &hbus->children); > -- > 2.7.4 >