x86: Use __builtin_object_size() to validate the buffer size for copy_from_user()

[mv-sheeva.git] / arch / x86 / include / asm / uaccess_64.h

diff --git a/arch/x86/include/asm/uaccess_64.h b/arch/x86/include/asm/uaccess_64.h
index db24b215fc50668bcf3f9da0f6757016aab7956e..ce6fec7ce38d403bd986651c19999bdb266f9fd5 100644 (file)
--- a/arch/x86/include/asm/uaccess_64.h
+++ b/arch/x86/include/asm/uaccess_64.h
@@ -21,10 +21,27 @@ copy_user_generic(void *to, const void *from, unsigned len);
 __must_check unsigned long
 copy_to_user(void __user *to, const void *from, unsigned len);
 __must_check unsigned long
-copy_from_user(void *to, const void __user *from, unsigned len);
+_copy_from_user(void *to, const void __user *from, unsigned len);
 __must_check unsigned long
 copy_in_user(void __user *to, const void __user *from, unsigned len);
 
+static inline unsigned long __must_check copy_from_user(void *to,
+                                         const void __user *from,
+                                         unsigned long n)
+{
+       int sz = __compiletime_object_size(to);
+       int ret = -EFAULT;
+
+       if (likely(sz == -1 || sz >= n))
+               ret = _copy_from_user(to, from, n);
+#ifdef CONFIG_DEBUG_VM
+       else
+               WARN(1, "Buffer overflow detected!\n");
+#endif
+       return ret;
+}
+
+
 static __always_inline __must_check
 int __copy_from_user(void *dst, const void __user *src, unsigned size)
 {