Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755076AbaDBBdE (ORCPT ); Tue, 1 Apr 2014 21:33:04 -0400 Received: from mx1.redhat.com ([209.132.183.28]:60159 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751626AbaDBBdC (ORCPT ); Tue, 1 Apr 2014 21:33:02 -0400 From: Bandan Das To: Bjorn Helgaas Cc: Alex Williamson , linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v3] PCI: rework new_id interface for known vendor/device values Date: Tue, 01 Apr 2014 21:32:59 -0400 Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.3 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org While using the new_id interface, the user can unintentionally feed incorrect values if the driver static table has a matching entry. This is possible since only the device and vendor fields are mandatory and the rest are optional. As a result, store_new_id will fill in default values that are then passed on to the driver and can have unintended consequences. As an example, consider the ixgbe driver and the 82599EB network card : echo "8086 10fb" > /sys/bus/pci/drivers/ixgbe/new_id This will pass a driver_data value of 0 to the driver whereas the index 0 in ixgbe actually points to a different set of card operations. This change returns an error if the user attempts to add a dynid for a vendor/device combination for which a static entry already exists. However, if the user intentionally wants a different set of values, she must provide all the 7 fields and that will be accepted. In KVM/device assignment scenario, the user might want to bind a device back to the host driver by writing to new_id and trip on a possible null pointer dereference. Signed-off-by: Bandan Das --- v3: relocate pdev decl v2: 1. Return error if there is a matching static entry and change commit message to reflect this behavior 3. Fill in a pdev and call pci_match_id instead of creating a new matching function 4. Change commit message to reflect that libvirt does not depend on this behavior drivers/pci/pci-driver.c | 22 +++++++++++++++++++++- 1 file changed, 21 insertions(+), 1 deletion(-) diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c index 25f0bc6..a65a014 100644 --- a/drivers/pci/pci-driver.c +++ b/drivers/pci/pci-driver.c @@ -107,7 +107,7 @@ store_new_id(struct device_driver *driver, const char *buf, size_t count) subdevice=PCI_ANY_ID, class=0, class_mask=0; unsigned long driver_data=0; int fields=0; - int retval; + int retval = 0; fields = sscanf(buf, "%x %x %x %x %x %x %lx", &vendor, &device, &subvendor, &subdevice, @@ -115,6 +115,26 @@ store_new_id(struct device_driver *driver, const char *buf, size_t count) if (fields < 2) return -EINVAL; + if (fields != 7) { + struct pci_dev *pdev = kzalloc(sizeof(*pdev), GFP_KERNEL); + if (!pdev) + return -ENOMEM; + + pdev->vendor = vendor; + pdev->device = device; + pdev->subsystem_vendor = subvendor; + pdev->subsystem_device = subdevice; + pdev->class = class; + + if (pci_match_id(pdrv->id_table, pdev)) + retval = -EEXIST; + + kfree(pdev); + + if (retval) + return retval; + } + /* Only accept driver_data values that match an existing id_table entry */ if (ids) { -- 1.8.3.1 -- 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/