Do more checking in the SRAT header code

- Check if the processor/memory affinity entries are long enough
according to the ACPI 3.0 spec.
- Ignore memory affinity entries that define a zero length region.

All based on BIOS issues found in the field @)

Signed-off-by: Andi Kleen <ak@suse.de>

Index: linux/arch/x86_64/mm/srat.c
===================================================================
--- linux.orig/arch/x86_64/mm/srat.c
+++ linux/arch/x86_64/mm/srat.c
@@ -131,7 +131,17 @@ void __init
 acpi_numa_processor_affinity_init(struct acpi_table_processor_affinity *pa)
 {
 	int pxm, node;
-	if (srat_disabled() || pa->flags.enabled == 0)
+	if (srat_disabled()) 
+		return;
+	if (pa->header.length < offsetof(typeof(*pa), flags)+sizeof(pa->flags)) {
+		printk(KERN_WARNING
+   "SRAT: Processor affinity for PXM %d APIC %u too short (%u). Ignored.\n",
+			pa->proximity_domain,
+			pa->apic_id,
+			pa->header.length);
+		return;
+	}
+	if (pa->flags.enabled == 0)
 		return;
 	pxm = pa->proximity_domain;
 	node = setup_node(pxm);
@@ -155,17 +165,33 @@ acpi_numa_memory_affinity_init(struct ac
 	int node, pxm;
 	int i;
 
-	if (srat_disabled() || ma->flags.enabled == 0)
+	if (srat_disabled())
+		return;
+	if (ma->header.length < offsetof(typeof(*ma), flags)+sizeof(ma->flags)) {
+		printk(KERN_WARNING
+	  "SRAT: Memory affinity for PXM %d too short (%u bytes). Ignored.\n",
+			ma->proximity_domain,
+			ma->header.length);
+		return;
+	}
+	if (ma->flags.enabled == 0)
 		return;
+	start = ma->base_addr_lo | ((u64)ma->base_addr_hi << 32);
+	end = start + (ma->length_lo | ((u64)ma->length_hi << 32));
 	pxm = ma->proximity_domain;
+	if (start == end) { 
+		printk(KERN_WARNING
+	"SRAT: Memory affinity for PXM %u empty (%lx-%lx). Ignored.\n",
+			pxm, 
+			start, end);
+		return;
+	}
 	node = setup_node(pxm);
 	if (node < 0) {
 		printk(KERN_ERR "SRAT: Too many proximity domains.\n");
 		bad_srat();
 		return;
 	}
-	start = ma->base_addr_lo | ((u64)ma->base_addr_hi << 32);
-	end = start + (ma->length_lo | ((u64)ma->length_hi << 32));
 	/* It is fine to add this area to the nodes data it will be used later*/
 	if (ma->flags.hot_pluggable == 1)
 		printk(KERN_INFO "SRAT: hot plug zone found %lx - %lx \n",