iscsi_ibft: Don't limits Targets and NICs to two

According to iSCSI Boot Firmware Table Version 1.03 [1], the length of
the control table is ">= 18", where the optional expansion structure
pointer follow the mandatory ones. This allows for more than two NICs
and Targets.

[1] ftp://ftp.software.ibm.com/systems/support/bladecenter/iscsi_boot_firmware_table_v1.03.pdf

Let's enforce the minimum length of the control structure instead
instead of limiting it to the smallest allowed size.
Signed-off-by: Lubomir Rintel <lkundrak@v3.sk>
Signed-off-by: Konrad Rzeszutek Wilk <konrad@darnok.org>

drivers/firmware/iscsi_ibft.c

@@ -104,6 +104,7 @@ struct ibft_control {
 	u16 tgt0_off;
 	u16 nic1_off;
 	u16 tgt1_off;
+	u16 expansion[0];
 } __attribute__((__packed__));
 
 struct ibft_initiator {
@@ -235,7 +236,7 @@ static int ibft_verify_hdr(char *t, struct ibft_hdr *hdr, int id, int length)
 				"found %d instead!\n", t, id, hdr->id);
 		return -ENODEV;
 	}
-	if (hdr->length != length) {
+	if (length && hdr->length != length) {
 		printk(KERN_ERR "iBFT error: We expected the %s " \
 				"field header.length to have %d but " \
 				"found %d instead!\n", t, length, hdr->length);
@@ -749,16 +750,16 @@ static int __init ibft_register_kobjects(struct acpi_table_ibft *header)
 	control = (void *)header + sizeof(*header);
 	end = (void *)control + control->hdr.length;
 	eot_offset = (void *)header + header->header.length - (void *)control;
-	rc = ibft_verify_hdr("control", (struct ibft_hdr *)control, id_control,
-			     sizeof(*control));
+	rc = ibft_verify_hdr("control", (struct ibft_hdr *)control, id_control, 0);
 
 	/* iBFT table safety checking */
 	rc |= ((control->hdr.index) ? -ENODEV : 0);
+	rc |= ((control->hdr.length < sizeof(*control)) ? -ENODEV : 0);
 	if (rc) {
 		printk(KERN_ERR "iBFT error: Control header is invalid!\n");
 		return rc;
 	}
-	for (ptr = &control->initiator_off; ptr < end; ptr += sizeof(u16)) {
+	for (ptr = &control->initiator_off; ptr + sizeof(u16) <= end; ptr += sizeof(u16)) {
 		offset = *(u16 *)ptr;
 		if (offset && offset < header->header.length &&
 						offset < eot_offset) {