--- linux-2.6.5/arch/i386/kernel/cpuid.c	2004-04-04 05:36:12.000000000 +0200
+++ linux/arch/i386/kernel/cpuid.c	2004-05-18 20:47:05.000000000 +0200
@@ -135,7 +135,7 @@
   int cpu = iminor(file->f_dentry->d_inode);
   struct cpuinfo_x86 *c = &(cpu_data)[cpu];
 
-  if (!cpu_online(cpu))
+  if (cpu >= num_possible_cpus() || !cpu_online(cpu))
     return -ENXIO;		/* No such CPU */
   if ( c->cpuid_level < 0 )
     return -EIO;		/* CPUID not supported */