From 07f78b308984042dde424191ab8f3237bcf6a0d1 Mon Sep 17 00:00:00 2001
From: Al Viro <viro@zeniv.linux.org.uk>
Date: Sun, 19 Mar 2017 15:07:21 -0400
Subject: cris: don't rely upon __copy_user_zeroing() zeroing the tail

we want to get rid of it; unfortunately, it's tangled as hell, so
it'll take many steps, more's the pity.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
 arch/cris/include/asm/uaccess.h | 16 +++++++++-------
 1 file changed, 9 insertions(+), 7 deletions(-)

(limited to 'arch/cris')

diff --git a/arch/cris/include/asm/uaccess.h b/arch/cris/include/asm/uaccess.h
index f62f546720a9..c8858e15d709 100644
--- a/arch/cris/include/asm/uaccess.h
+++ b/arch/cris/include/asm/uaccess.h
@@ -338,14 +338,16 @@ static inline size_t clear_user(void __user *to, size_t n)
 
 static inline size_t copy_from_user(void *to, const void __user *from, size_t n)
 {
-	if (unlikely(!access_ok(VERIFY_READ, from, n))) {
-		memset(to, 0, n);
-		return n;
+	size_t res = n;
+	if (likely(access_ok(VERIFY_READ, from, n))) {
+		if (__builtin_constant_p(n))
+			res = __constant_copy_from_user(to, from, n);
+		else
+			res = __copy_user_zeroing(to, from, n);
 	}
-	if (__builtin_constant_p(n))
-		return __constant_copy_from_user(to, from, n);
-	else
-		return __copy_user_zeroing(to, from, n);
+	if (unlikely(res))
+		memset(to + n - res , 0, res);
+	return res;
 }
 
 static inline size_t copy_to_user(void __user *to, const void *from, size_t n)
-- 
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