From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753897AbcARDYu (ORCPT ); Sun, 17 Jan 2016 22:24:50 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:59424 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753144AbcARDWF (ORCPT ); Sun, 17 Jan 2016 22:22:05 -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, "Jan Beulich" , "Konrad Rzeszutek Wilk" , "David Vrabel" Date: Mon, 18 Jan 2016 03:18:35 +0000 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.2 25/70] xen/pciback: Return error on XEN_PCI_OP_enable_msi when device has MSI or MSI-X enabled In-Reply-To: X-SA-Exim-Connect-IP: 192.168.4.247 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 3.2.76-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Konrad Rzeszutek Wilk commit 56441f3c8e5bd45aab10dd9f8c505dd4bec03b0d upstream. The guest sequence of: a) XEN_PCI_OP_enable_msi b) XEN_PCI_OP_enable_msi c) XEN_PCI_OP_disable_msi results in hitting an BUG_ON condition in the msi.c code. The MSI code uses an dev->msi_list to which it adds MSI entries. Under the above conditions an BUG_ON() can be hit. The device passed in the guest MUST have MSI capability. The a) adds the entry to the dev->msi_list and sets msi_enabled. The b) adds a second entry but adding in to SysFS fails (duplicate entry) and deletes all of the entries from msi_list and returns (with msi_enabled is still set). c) pci_disable_msi passes the msi_enabled checks and hits: BUG_ON(list_empty(dev_to_msi_list(&dev->dev))); and blows up. The patch adds a simple check in the XEN_PCI_OP_enable_msi to guard against that. The check for msix_enabled is not stricly neccessary. This is part of XSA-157. Reviewed-by: David Vrabel Reviewed-by: Jan Beulich Signed-off-by: Konrad Rzeszutek Wilk Signed-off-by: Ben Hutchings --- drivers/xen/xen-pciback/pciback_ops.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) --- a/drivers/xen/xen-pciback/pciback_ops.c +++ b/drivers/xen/xen-pciback/pciback_ops.c @@ -142,7 +142,12 @@ int xen_pcibk_enable_msi(struct xen_pcib if (unlikely(verbose_request)) printk(KERN_DEBUG DRV_NAME ": %s: enable MSI\n", pci_name(dev)); - status = pci_enable_msi(dev); + if (dev->msi_enabled) + status = -EALREADY; + else if (dev->msix_enabled) + status = -ENXIO; + else + status = pci_enable_msi(dev); if (status) { pr_warn_ratelimited(DRV_NAME ": %s: error enabling MSI for guest %u: err %d\n",