igb: Fix null pointer dereference

The max_vfs= option has always been self limiting to the number of VFs
supported by the device.  fa44f2f1 added SR-IOV configuration via
sysfs, but in the process broke this self correction factor.  The
failing path is:

igb_probe
  igb_sw_init
    if (max_vfs > 7) {
        adapter->vfs_allocated_count = 7;
    ...
    igb_probe_vfs
    igb_enable_sriov(, max_vfs)
      if (num_vfs > 7) {
        err = -EPERM;
        ...

This leaves vfs_allocated_count = 7 and vf_data = NULL, so we bomb out
when igb_probe finally calls igb_reset.  It seems like a really bad
idea, and somewhat pointless, to set vfs_allocated_count separate from
vf_data, but limiting max_vfs is enough to avoid the null pointer.

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Acked-by: Greg Rose <gregory.v.rose@intel.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

diff --git a/drivers/net/ethernet/intel/igb/igb_main.c b/drivers/net/ethernet/intel/igb/igb_main.c
index 4dbd62968c7a18090a61029249c04f6ee3b1335e..2ae888678b23574609e10f8c1d746ae0ae4107c9 100644 (file)
--- a/drivers/net/ethernet/intel/igb/igb_main.c
+++ b/drivers/net/ethernet/intel/igb/igb_main.c
@@ -2652,7 +2652,7 @@ static int igb_sw_init(struct igb_adapter *adapter)
                if (max_vfs > 7) {
                        dev_warn(&pdev->dev,
                                 "Maximum of 7 VFs per PF, using max\n");
-                       adapter->vfs_allocated_count = 7;
+                       max_vfs = adapter->vfs_allocated_count = 7;
                } else
                        adapter->vfs_allocated_count = max_vfs;
                if (adapter->vfs_allocated_count)