netdev - [PATCH 1/2] tun: Use memdup_user() rather than duplicating its implementation

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Message-ID: <a2ee9925-1241-0328-6d35-9a9c9f567ea4@users.sourceforge.net>
Date:   Sat, 20 Aug 2016 09:34:56 +0200
From:   SF Markus Elfring <elfring@...rs.sourceforge.net>
To:     netdev@...r.kernel.org, "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jason Wang <jasowang@...hat.com>,
        "Michael S. Tsirkin" <mst@...hat.com>,
        Mike Rapoport <rppt@...ux.vnet.ibm.com>,
        Paolo Abeni <pabeni@...hat.com>,
        Soheil Hassas Yeganeh <soheil@...gle.com>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        kernel-janitors@...r.kernel.org,
        Julia Lawall <julia.lawall@...6.fr>
Subject: [PATCH 1/2] tun: Use memdup_user() rather than duplicating its
 implementation

From: Markus Elfring <elfring@...rs.sourceforge.net>
Date: Sat, 20 Aug 2016 08:54:15 +0200

Reuse existing functionality from memdup_user() instead of keeping
duplicate source code.

This issue was detected by using the Coccinelle software.

Signed-off-by: Markus Elfring <elfring@...rs.sourceforge.net>
---
 drivers/net/tun.c | 11 +++--------
 1 file changed, 3 insertions(+), 8 deletions(-)

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 9c8b5bc..a1aeccb 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -731,14 +731,9 @@ static int update_filter(struct tap_filter *filter, void __user *arg)
 	}
 
 	alen = ETH_ALEN * uf.count;
-	addr = kmalloc(alen, GFP_KERNEL);
-	if (!addr)
-		return -ENOMEM;
-
-	if (copy_from_user(addr, arg + sizeof(uf), alen)) {
-		err = -EFAULT;
-		goto done;
-	}
+	addr = memdup_user(arg + sizeof(uf), alen);
+	if (IS_ERR(addr))
+		return PTR_ERR(addr);
 
 	/* The filter is updated without holding any locks. Which is
 	 * perfectly safe. We disable it first and in the worst
-- 
2.9.3