From mboxrd@z Thu Jan 1 00:00:00 1970 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754733AbdBEU1n (ORCPT + 2 others); Sun, 5 Feb 2017 15:27:43 -0500 Received: from wtarreau.pck.nerim.net ([62.212.114.60]:27497 "EHLO 1wt.eu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752832AbdBETWx (ORCPT ); Sun, 5 Feb 2017 14:22:53 -0500 From: Willy Tarreau To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, linux@roeck-us.net Cc: Konrad Rzeszutek Wilk , Willy Tarreau Subject: [PATCH 3.10 038/319] xen/pciback: Return error on XEN_PCI_OP_enable_msi when device has MSI or MSI-X enabled Date: Sun, 5 Feb 2017 20:20:25 +0100 Message-Id: <1486322486-8024-9-git-send-email-w@1wt.eu> X-Mailer: git-send-email 2.8.0.rc2.1.gbe9624a In-Reply-To: <1486322486-8024-1-git-send-email-w@1wt.eu> References: <1486322486-8024-1-git-send-email-w@1wt.eu> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Return-Path: 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: Willy Tarreau --- drivers/xen/xen-pciback/pciback_ops.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/drivers/xen/xen-pciback/pciback_ops.c b/drivers/xen/xen-pciback/pciback_ops.c index 32f83f0..0dadc2a 100644 --- a/drivers/xen/xen-pciback/pciback_ops.c +++ b/drivers/xen/xen-pciback/pciback_ops.c @@ -141,7 +141,12 @@ int xen_pcibk_enable_msi(struct xen_pcibk_device *pdev, 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", -- 2.8.0.rc2.1.gbe9624a