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

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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>
This commit is contained in:
Bandan Das 2014-04-01 21:32:59 -04:00 committed by Bjorn Helgaas
parent 7c82126a94
commit 8895d3bcb8
1 changed files with 21 additions and 1 deletions
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22
drivers/pci/pci-driver.c
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@ -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) {