[S390] uaccess: implement strict user copy checks

[net-next-2.6.git] / arch / s390 / include / asm / uaccess.h

diff --git a/arch/s390/include/asm/uaccess.h b/arch/s390/include/asm/uaccess.h
index cbf0a8745bf419cf251a77aa2959e580ef31efe8..d6b1ed0ec52b3b8bb5a27537a2fa378cfddce34b 100644 (file)
--- a/arch/s390/include/asm/uaccess.h
+++ b/arch/s390/include/asm/uaccess.h
@@ -265,6 +265,12 @@ __copy_from_user(void *to, const void __user *from, unsigned long n)
                return uaccess.copy_from_user(n, from, to);
 }
 
+extern void copy_from_user_overflow(void)
+#ifdef CONFIG_DEBUG_STRICT_USER_COPY_CHECKS
+__compiletime_warning("copy_from_user() buffer size is not provably correct")
+#endif
+;
+
 /**
  * copy_from_user: - Copy a block of data from user space.
  * @to:   Destination address, in kernel space.
@@ -284,7 +290,13 @@ __copy_from_user(void *to, const void __user *from, unsigned long n)
 static inline unsigned long __must_check
 copy_from_user(void *to, const void __user *from, unsigned long n)
 {
+       unsigned int sz = __compiletime_object_size(to);
+
        might_fault();
+       if (unlikely(sz != -1 && sz < n)) {
+               copy_from_user_overflow();
+               return n;
+       }
        if (access_ok(VERIFY_READ, from, n))
                n = __copy_from_user(to, from, n);
        else