4.7-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Al Viro <v...@zeniv.linux.org.uk>

commit 2561d309dfd1555e781484af757ed0115035ddb3 upstream.

it should clear the destination even when access_ok() fails.

Signed-off-by: Al Viro <v...@zeniv.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>

---
 arch/alpha/include/asm/uaccess.h |   19 ++++++++-----------
 1 file changed, 8 insertions(+), 11 deletions(-)

--- a/arch/alpha/include/asm/uaccess.h
+++ b/arch/alpha/include/asm/uaccess.h
@@ -371,14 +371,6 @@ __copy_tofrom_user_nocheck(void *to, con
        return __cu_len;
 }
 
-extern inline long
-__copy_tofrom_user(void *to, const void *from, long len, const void __user 
*validate)
-{
-       if (__access_ok((unsigned long)validate, len, get_fs()))
-               len = __copy_tofrom_user_nocheck(to, from, len);
-       return len;
-}
-
 #define __copy_to_user(to, from, n)                                    \
 ({                                                                     \
        __chk_user_ptr(to);                                             \
@@ -393,17 +385,22 @@ __copy_tofrom_user(void *to, const void
 #define __copy_to_user_inatomic __copy_to_user
 #define __copy_from_user_inatomic __copy_from_user
 
-
 extern inline long
 copy_to_user(void __user *to, const void *from, long n)
 {
-       return __copy_tofrom_user((__force void *)to, from, n, to);
+       if (likely(__access_ok((unsigned long)to, n, get_fs())))
+               n = __copy_tofrom_user_nocheck((__force void *)to, from, n);
+       return n;
 }
 
 extern inline long
 copy_from_user(void *to, const void __user *from, long n)
 {
-       return __copy_tofrom_user(to, (__force void *)from, n, from);
+       if (likely(__access_ok((unsigned long)from, n, get_fs())))
+               n = __copy_tofrom_user_nocheck(to, (__force void *)from, n);
+       else
+               memset(to, 0, n);
+       return n;
 }
 
 extern void __do_clear_user(void);


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