linux-kernel - [PATCH 4.9 16/59] rtnl: stats - add missing netlink message size checks

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Message-Id: <20170113113839.979664599@linuxfoundation.org>
Date:   Fri, 13 Jan 2017 13:01:23 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Mathias Krause <minipli@...glemail.com>,
        Roopa Prabhu <roopa@...ulusnetworks.com>,
        "David S. Miller" <davem@...emloft.net>
Subject: [PATCH 4.9 16/59] rtnl: stats - add missing netlink message size checks

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

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

From: Mathias Krause <minipli@...glemail.com>


[ Upstream commit 4775cc1f2d5abca894ac32774eefc22c45347d1c ]

We miss to check if the netlink message is actually big enough to contain
a struct if_stats_msg.

Add a check to prevent userland from sending us short messages that would
make us access memory beyond the end of the message.

Fixes: 10c9ead9f3c6 ("rtnetlink: add new RTM_GETSTATS message to dump...")
Signed-off-by: Mathias Krause <minipli@...glemail.com>
Cc: Roopa Prabhu <roopa@...ulusnetworks.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 net/core/rtnetlink.c |    6 ++++++
 1 file changed, 6 insertions(+)

--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -3886,6 +3886,9 @@ static int rtnl_stats_get(struct sk_buff
 	u32 filter_mask;
 	int err;
 
+	if (nlmsg_len(nlh) < sizeof(*ifsm))
+		return -EINVAL;
+
 	ifsm = nlmsg_data(nlh);
 	if (ifsm->ifindex > 0)
 		dev = __dev_get_by_index(net, ifsm->ifindex);
@@ -3935,6 +3938,9 @@ static int rtnl_stats_dump(struct sk_buf
 
 	cb->seq = net->dev_base_seq;
 
+	if (nlmsg_len(cb->nlh) < sizeof(*ifsm))
+		return -EINVAL;
+
 	ifsm = nlmsg_data(cb->nlh);
 	filter_mask = ifsm->filter_mask;
 	if (!filter_mask)