Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S966810AbcCPLBu (ORCPT ); Wed, 16 Mar 2016 07:01:50 -0400 Received: from mx2.suse.de ([195.135.220.15]:47249 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S966666AbcCPLAQ (ORCPT ); Wed, 16 Mar 2016 07:00:16 -0400 X-Amavis-Alert: BAD HEADER SECTION, Duplicate header field: "References" From: Jiri Slaby To: stable@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Konrad Rzeszutek Wilk , Jiri Slaby Subject: [PATCH 3.12 54/58] xen/pciback: Return error on XEN_PCI_OP_enable_msix when device has MSI or MSI-X enabled Date: Wed, 16 Mar 2016 11:59:39 +0100 Message-Id: X-Mailer: git-send-email 2.7.3 In-Reply-To: <377b71e18f20d69b0df301ce7040554f40ba9651.1458125909.git.jslaby@suse.cz> References: <377b71e18f20d69b0df301ce7040554f40ba9651.1458125909.git.jslaby@suse.cz> In-Reply-To: References: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2172 Lines: 64 From: Konrad Rzeszutek Wilk 3.12-stable review patch. If anyone has any objections, please let me know. =============== commit 5e0ce1455c09dd61d029b8ad45d82e1ac0b6c4c9 upstream. The guest sequence of: a) XEN_PCI_OP_enable_msix b) XEN_PCI_OP_enable_msix results in hitting an NULL pointer due to using freed pointers. The device passed in the guest MUST have MSI-X capability. The a) constructs and SysFS representation of MSI and MSI groups. The b) adds a second set of them but adding in to SysFS fails (duplicate entry). 'populate_msi_sysfs' frees the newly allocated msi_irq_groups (note that in a) pdev->msi_irq_groups is still set) and also free's ALL of the MSI-X entries of the device (the ones allocated in step a) and b)). The unwind code: 'free_msi_irqs' deletes all the entries and tries to delete the pdev->msi_irq_groups (which hasn't been set to NULL). However the pointers in the SysFS are already freed and we hit an NULL pointer further on when 'strlen' is attempted on a freed pointer. The patch adds a simple check in the XEN_PCI_OP_enable_msix to guard against that. The check for msi_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: Jiri Slaby --- drivers/xen/xen-pciback/pciback_ops.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/drivers/xen/xen-pciback/pciback_ops.c b/drivers/xen/xen-pciback/pciback_ops.c index 37452734af98..32cbafcece76 100644 --- a/drivers/xen/xen-pciback/pciback_ops.c +++ b/drivers/xen/xen-pciback/pciback_ops.c @@ -206,9 +206,16 @@ int xen_pcibk_enable_msix(struct xen_pcibk_device *pdev, if (unlikely(verbose_request)) printk(KERN_DEBUG DRV_NAME ": %s: enable MSI-X\n", pci_name(dev)); + if (op->value > SH_INFO_MAX_VEC) return -EINVAL; + if (dev->msix_enabled) + return -EALREADY; + + if (dev->msi_enabled) + return -ENXIO; + entries = kmalloc(op->value * sizeof(*entries), GFP_KERNEL); if (entries == NULL) return -ENOMEM; -- 2.7.3