x86, e820: Guard against array overflowed in __e820_add_region()

Better to be paranoid against unpredicted nr_map modifications.
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
LKML-Reference: <20090824175551.146070377@openvz.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/x86/kernel/e820.c

@@ -115,7 +115,7 @@ static void __init __e820_add_region(struct e820map *e820x, u64 start, u64 size,
 {
 	int x = e820x->nr_map;
 
-	if (x == ARRAY_SIZE(e820x->map)) {
+	if (x >= ARRAY_SIZE(e820x->map)) {
 		printk(KERN_ERR "Ooops! Too many entries in the memory map!\n");
 		return;
 	}