Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751655AbaDAWpF (ORCPT ); Tue, 1 Apr 2014 18:45:05 -0400 Received: from mx1.redhat.com ([209.132.183.28]:27657 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751371AbaDAWpC (ORCPT ); Tue, 1 Apr 2014 18:45:02 -0400 Message-ID: <1396392298.476.226.camel@ul30vt.home> Subject: Re: [PATCH v2] PCI: rework new_id interface for known vendor/device values From: Alex Williamson To: Bandan Das Cc: Bjorn Helgaas , linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org Date: Tue, 01 Apr 2014 16:44:58 -0600 In-Reply-To: References: <1396388707.476.188.camel@ul30vt.home> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2014-04-01 at 18:00 -0400, Bandan Das wrote: > Alex Williamson writes: > > > On Tue, 2014-04-01 at 17:22 -0400, Bandan Das wrote: > >> 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 > >> --- > >> 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 | 23 ++++++++++++++++++++++- > >> 1 file changed, 22 insertions(+), 1 deletion(-) > >> > >> diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c > >> index 25f0bc6..493514e 100644 > >> --- a/drivers/pci/pci-driver.c > >> +++ b/drivers/pci/pci-driver.c > >> @@ -103,11 +103,12 @@ store_new_id(struct device_driver *driver, const char *buf, size_t count) > >> { > >> struct pci_driver *pdrv = to_pci_driver(driver); > >> const struct pci_device_id *ids = pdrv->id_table; > >> + struct pci_dev *pdev; > >> __u32 vendor, device, subvendor=PCI_ANY_ID, > >> 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 +116,26 @@ store_new_id(struct device_driver *driver, const char *buf, size_t count) > >> if (fields < 2) > >> return -EINVAL; > >> > >> + if (fields != 7) { > > > > nit, pdev could be declared within this scope. > > Ok, will spin a new one. > > >> + 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; > > > > Why not class_mask? > pdev->class_mask isn't used anywhere. Ah, you're right. Ok. Thanks, Alex > >> + > >> + 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) { -- 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/