PCI: Fail new_id for vendor/device values already built into driver

While using the sysfs 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 pci_device_id with driver_data = 0 to ixgbe_probe(), which
uses that zero to index a table of card operations.  The zeroth entry of
the table does *not* correspond to the 82599 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.

[bhelgaas: drop KVM text since the problem isn't KVM-specific]
Signed-off-by: Bandan Das <bsd@redhat.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Alex Williamson <alex.williamson@redhat.com>

diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c
index d911e0c..650ce89 100644 (file)
--- 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) {