linux-kernel - [PATCH 3.12 105/119] score: fix copy_from

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Message-Id: <20f17babfafe6641a200b49b572e61464c475a99.1475144721.git.jslaby@suse.cz>
Date:   Thu, 29 Sep 2016 12:25:41 +0200
From:   Jiri Slaby <jslaby@...e.cz>
To:     stable@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, Al Viro <viro@...iv.linux.org.uk>,
        Jiri Slaby <jslaby@...e.cz>
Subject: [PATCH 3.12 105/119] score: fix copy_from_user() and friends

From: Al Viro <viro@...iv.linux.org.uk>

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

===============

commit b615e3c74621e06cd97f86373ca90d43d6d998aa upstream.

Signed-off-by: Al Viro <viro@...iv.linux.org.uk>
Signed-off-by: Jiri Slaby <jslaby@...e.cz>
---
 arch/score/include/asm/uaccess.h | 41 ++++++++++++++++++++--------------------
 1 file changed, 20 insertions(+), 21 deletions(-)

diff --git a/arch/score/include/asm/uaccess.h b/arch/score/include/asm/uaccess.h
index c882d961e5b8..69326dfb894d 100644
--- a/arch/score/include/asm/uaccess.h
+++ b/arch/score/include/asm/uaccess.h
@@ -296,35 +296,34 @@ extern int __copy_tofrom_user(void *to, const void *from, unsigned long len);
 static inline unsigned long
 copy_from_user(void *to, const void *from, unsigned long len)
 {
-	unsigned long over;
+	unsigned long res = len;
 
-	if (access_ok(VERIFY_READ, from, len))
-		return __copy_tofrom_user(to, from, len);
+	if (likely(access_ok(VERIFY_READ, from, len)))
+		res = __copy_tofrom_user(to, from, len);
 
-	if ((unsigned long)from < TASK_SIZE) {
-		over = (unsigned long)from + len - TASK_SIZE;
-		return __copy_tofrom_user(to, from, len - over) + over;
-	}
-	return len;
+	if (unlikely(res))
+		memset(to + (len - res), 0, res);
+
+	return res;
 }
 
 static inline unsigned long
 copy_to_user(void *to, const void *from, unsigned long len)
 {
-	unsigned long over;
-
-	if (access_ok(VERIFY_WRITE, to, len))
-		return __copy_tofrom_user(to, from, len);
+	if (likely(access_ok(VERIFY_WRITE, to, len)))
+		len = __copy_tofrom_user(to, from, len);
 
-	if ((unsigned long)to < TASK_SIZE) {
-		over = (unsigned long)to + len - TASK_SIZE;
-		return __copy_tofrom_user(to, from, len - over) + over;
-	}
 	return len;
 }
 
-#define __copy_from_user(to, from, len)	\
-		__copy_tofrom_user((to), (from), (len))
+static inline unsigned long
+__copy_from_user(void *to, const void *from, unsigned long len)
+{
+	unsigned long left = __copy_tofrom_user(to, from, len);
+	if (unlikely(left))
+		memset(to + (len - left), 0, left);
+	return left;
+}
 
 #define __copy_to_user(to, from, len)		\
 		__copy_tofrom_user((to), (from), (len))
@@ -338,17 +337,17 @@ __copy_to_user_inatomic(void *to, const void *from, unsigned long len)
 static inline unsigned long
 __copy_from_user_inatomic(void *to, const void *from, unsigned long len)
 {
-	return __copy_from_user(to, from, len);
+	return __copy_tofrom_user(to, from, len);
 }
 
-#define __copy_in_user(to, from, len)	__copy_from_user(to, from, len)
+#define __copy_in_user(to, from, len)	__copy_tofrom_user(to, from, len)
 
 static inline unsigned long
 copy_in_user(void *to, const void *from, unsigned long len)
 {
 	if (access_ok(VERIFY_READ, from, len) &&
 		      access_ok(VERFITY_WRITE, to, len))
-		return copy_from_user(to, from, len);
+		return __copy_tofrom_user(to, from, len);
 }
 
 /*
-- 
2.10.0