xenbus: don't BUG() on user mode induced condition

[pandora-kernel.git] / include / asm-generic / uaccess.h

diff --git a/include/asm-generic/uaccess.h b/include/asm-generic/uaccess.h
index ac68c99..5ba2c45 100644 (file)
--- a/include/asm-generic/uaccess.h
+++ b/include/asm-generic/uaccess.h
@@ -221,13 +221,17 @@ extern int __put_user_bad(void) __attribute__((noreturn));
        might_sleep();                                          \
        access_ok(VERIFY_READ, ptr, sizeof(*ptr)) ?             \
                __get_user(x, ptr) :                            \
-               -EFAULT;                                        \
+               ((x) = (__typeof__(*(ptr)))0,-EFAULT);          \
 })
 
 static inline int __get_user_fn(size_t size, const void __user *ptr, void *x)
 {
-       size = __copy_from_user(x, ptr, size);
-       return size ? -EFAULT : size;
+       size_t n = __copy_from_user(x, ptr, size);
+       if (unlikely(n)) {
+               memset(x + (size - n), 0, n);
+               return -EFAULT;
+       }
+       return 0;
 }
 
 extern int __get_user_bad(void) __attribute__((noreturn));
@@ -243,11 +247,13 @@ extern int __get_user_bad(void) __attribute__((noreturn));
 static inline long copy_from_user(void *to,
                const void __user * from, unsigned long n)
 {
+       unsigned long res = n;
        might_sleep();
-       if (access_ok(VERIFY_READ, from, n))
-               return __copy_from_user(to, from, n);
-       else
-               return n;
+       if (likely(access_ok(VERIFY_READ, from, n)))
+               res = __copy_from_user(to, from, n);
+       if (unlikely(res))
+               memset(to + (n - res), 0, res);
+       return res;
 }
 
 static inline long copy_to_user(void __user *to,