1 files changed, 26 insertions, 1 deletions

diff --git a/arch/x86/include/asm/uaccess_32.h b/arch/x86/include/asm/uaccess_32.h
index 632fb44b4cb..0c9825e97f3 100644
--- a/arch/x86/include/asm/uaccess_32.h
+++ b/arch/x86/include/asm/uaccess_32.h
@@ -187,9 +187,34 @@ __copy_from_user_inatomic_nocache(void *to, const void __user *from,
 
 unsigned long __must_check copy_to_user(void __user *to,
                                         const void *from, unsigned long n);
-unsigned long __must_check copy_from_user(void *to,
+unsigned long __must_check _copy_from_user(void *to,
                                           const void __user *from,
                                           unsigned long n);
+
+
+extern void copy_from_user_overflow(void)
+#ifdef CONFIG_DEBUG_STRICT_USER_COPY_CHECKS
+        __compiletime_error("copy_from_user() buffer size is not provably correct")
+#else
+        __compiletime_warning("copy_from_user() buffer size is not provably correct")
+#endif
+;
+
+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);
+        else
+                copy_from_user_overflow();
+
+        return ret;
+}
+
 long __must_check strncpy_from_user(char *dst, const char __user *src,
                                     long count);
 long __must_check __strncpy_from_user(char *dst,