[Xen-devel] [PATCH] x86: adjust microcode handling interface

["Jan Beulich" <jbeulich@xxxxxxxxxx>]

Confine the knowledge that the buffer gets accessed without use of
proper guest handle accessors to a single file.

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxxxx>

Index: 2006-09-21/xen/arch/x86/microcode.c
===================================================================
--- 2006-09-21.orig/xen/arch/x86/microcode.c    2006-08-28 12:24:50.000000000 
+0200
+++ 2006-09-21/xen/arch/x86/microcode.c 2006-09-28 12:24:53.000000000 +0200
@@ -455,7 +455,7 @@ static int do_microcode_update (void)
        return error;
 }
 
-int microcode_update(void *buf, unsigned long len)
+int microcode_update(XEN_GUEST_HANDLE(void) buf, unsigned long len)
 {
        int ret;
 
@@ -464,10 +464,15 @@ int microcode_update(void *buf, unsigned
                return -EINVAL;
        }
 
+       if (len != (typeof(user_buffer_size))len) {
+               printk(KERN_ERR "microcode: too much data\n");
+               return -E2BIG;
+       }
+
        mutex_lock(&microcode_mutex);
 
-       user_buffer = (void __user *) buf;
-       user_buffer_size = (int) len;
+       user_buffer = buf.p;
+       user_buffer_size = len;
 
        ret = do_microcode_update();
 
Index: 2006-09-21/xen/arch/x86/platform_hypercall.c
===================================================================
--- 2006-09-21.orig/xen/arch/x86/platform_hypercall.c   2006-09-28 
12:21:17.000000000 +0200
+++ 2006-09-21/xen/arch/x86/platform_hypercall.c        2006-09-28 
12:22:30.000000000 +0200
@@ -104,8 +104,8 @@ long do_platform_op(XEN_GUEST_HANDLE(xen
 
     case XENPF_microcode_update:
     {
-        extern int microcode_update(void *buf, unsigned long len);
-        ret = microcode_update(op->u.microcode.data.p,
+        extern int microcode_update(XEN_GUEST_HANDLE(void), unsigned long len);
+        ret = microcode_update(op->u.microcode.data,
                                op->u.microcode.length);
     }
     break;


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