linux-kernel - [PATCH 3.12 111/119] metag: copy_from_user() should zero the destination on access

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Message-Id: <dedf843d4ba72e5a1e0a1c05e173c80a0281625a.1475144721.git.jslaby@suse.cz>
Date:   Thu, 29 Sep 2016 12:25:47 +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 3.12 111/119] metag: copy_from_user() should zero the destination on access_ok() failure

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

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

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

commit 8ae95ed4ae5fc7c3391ed668b2014c9e2079533b upstream.

Acked-by: James Hogan <james.hogan@...tec.com>
Signed-off-by: Al Viro <viro@...iv.linux.org.uk>
Signed-off-by: Jiri Slaby <jslaby@...e.cz>
---
 arch/metag/include/asm/uaccess.h | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/metag/include/asm/uaccess.h b/arch/metag/include/asm/uaccess.h
index 0748b0a97986..7841f2290385 100644
--- a/arch/metag/include/asm/uaccess.h
+++ b/arch/metag/include/asm/uaccess.h
@@ -199,8 +199,9 @@ extern unsigned long __must_check __copy_user_zeroing(void *to,
 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;
 }
 
-- 
2.10.0