linux-kernel - [PATCH 3.12 089/123] ethtool: Use kcalloc instead of kmalloc for ethtool_get

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Message-Id: <3a5a55e659d34c1df941f8f362be02e9edc7011d.1446021555.git.jslaby@suse.cz>
Date:	Wed, 28 Oct 2015 14:53:20 +0100
From:	Jiri Slaby <jslaby@...e.cz>
To:	stable@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, Joe Perches <joe@...ches.com>,
	"David S . Miller" <davem@...emloft.net>,
	Jiri Slaby <jslaby@...e.cz>
Subject: [PATCH 3.12 089/123] ethtool: Use kcalloc instead of kmalloc for ethtool_get_strings

From: Joe Perches <joe@...ches.com>

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

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

[ Upstream commit 077cb37fcf6f00a45f375161200b5ee0cd4e937b ]

It seems that kernel memory can leak into userspace by a
kmalloc, ethtool_get_strings, then copy_to_user sequence.

Avoid this by using kcalloc to zero fill the copied buffer.

Signed-off-by: Joe Perches <joe@...ches.com>
Acked-by: Ben Hutchings <ben@...adent.org.uk>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Jiri Slaby <jslaby@...e.cz>
---
 net/core/ethtool.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/core/ethtool.c b/net/core/ethtool.c
index 78e9d9223e40..944c60ce15d8 100644
--- a/net/core/ethtool.c
+++ b/net/core/ethtool.c
@@ -1077,7 +1077,7 @@ static int ethtool_get_strings(struct net_device *dev, void __user *useraddr)
 
 	gstrings.len = ret;
 
-	data = kmalloc(gstrings.len * ETH_GSTRING_LEN, GFP_USER);
+	data = kcalloc(gstrings.len, ETH_GSTRING_LEN, GFP_USER);
 	if (!data)
 		return -ENOMEM;
 
-- 
2.6.2

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