PCI: Prevent out of bounds access in numa_node override

Commit 1266963 ("PCI: Prevent out of bounds access in numa_node
override") missed that the user-provided node could also be negative.
Handle this case as well to avoid out-of-bounds accesses to the
node_states[] array.  However, allow the special value -1, i.e.
NUMA_NO_NODE, to be able to set the 'no specific node' configuration.

Fixes: 1266963 ("PCI: Prevent out of bounds access in numa_node override")
Fixes: 63692df ("PCI: Allow numa_node override via sysfs")
Signed-off-by: Mathias Krause <minipli@googlemail.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
CC: Sasha Levin <sasha.levin@oracle.com>
CC: Prarit Bhargava <prarit@redhat.com>
CC: stable@vger.kernel.org	# v3.19+

drivers/pci/pci-sysfs.c

@@ -216,7 +216,10 @@ static ssize_t numa_node_store(struct device *dev,
 	if (ret)
 		return ret;
 
-	if (node >= MAX_NUMNODES || !node_online(node))
+	if ((node < 0 && node != NUMA_NO_NODE) || node >= MAX_NUMNODES)
+		return -EINVAL;
+
+	if (node != NUMA_NO_NODE && !node_online(node))
 		return -EINVAL;
 
 	add_taint(TAINT_FIRMWARE_WORKAROUND, LOCKDEP_STILL_OK);