netdev - [PATCH net-next] vxlan: fix incorrect nlattr access in MTU check

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Message-Id: <a6097db8a2ce4a13c108651c58a345ccff3505b0.1498565985.git.mschiffer@universe-factory.net>
Date:   Tue, 27 Jun 2017 14:42:43 +0200
From:   Matthias Schiffer <mschiffer@...verse-factory.net>
To:     davem@...emloft.net, jbenc@...hat.com, roopa@...ulusnetworks.com,
        pshelar@....org
Cc:     netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH net-next] vxlan: fix incorrect nlattr access in MTU check

The access to the wrong variable could lead to a NULL dereference and
possibly other invalid memory reads in vxlan newlink/changelink requests
with a IFLA_MTU attribute.

Fixes: a985343ba906 "vxlan: refactor verification and application of configuration"
Signed-off-by: Matthias Schiffer <mschiffer@...verse-factory.net>
---
 drivers/net/vxlan.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/vxlan.c b/drivers/net/vxlan.c
index 0dafd8e6c665..fd0ff97e3d81 100644
--- a/drivers/net/vxlan.c
+++ b/drivers/net/vxlan.c
@@ -2727,7 +2727,7 @@ static int vxlan_validate(struct nlattr *tb[], struct nlattr *data[],
 	}
 
 	if (tb[IFLA_MTU]) {
-		u32 mtu = nla_get_u32(data[IFLA_MTU]);
+		u32 mtu = nla_get_u32(tb[IFLA_MTU]);
 
 		if (mtu < ETH_MIN_MTU || mtu > ETH_MAX_MTU)
 			return -EINVAL;
-- 
2.13.2