linux-kernel - [PATCH 4.7 174/184] metag: copy_from_user() should zero the destination on access

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Message-Id: <20160922174056.145686739@linuxfoundation.org>
Date:   Thu, 22 Sep 2016 19:41:48 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, James Hogan <james.hogan@...tec.com>,
        Al Viro <viro@...iv.linux.org.uk>
Subject: [PATCH 4.7 174/184] metag: copy_from_user() should zero the destination on access_ok() failure

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

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

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

commit 8ae95ed4ae5fc7c3391ed668b2014c9e2079533b upstream.

Acked-by: James Hogan <james.hogan@...tec.com>
Signed-off-by: Al Viro <viro@...iv.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 arch/metag/include/asm/uaccess.h |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/arch/metag/include/asm/uaccess.h
+++ b/arch/metag/include/asm/uaccess.h
@@ -204,8 +204,9 @@ extern unsigned long __must_check __copy
 static inline unsigned long
 copy_from_user(void *to, const void __user *from, unsigned long n)
 {
-	if (access_ok(VERIFY_READ, from, n))
+	if (likely(access_ok(VERIFY_READ, from, n)))
 		return __copy_user_zeroing(to, from, n);
+	memset(to, 0, n);
 	return n;
 }