From: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
Date: Tue, 3 Oct 2017 13:20:48 +0300
Subject: net: rtnetlink: fix info leak in RTM_GETSTATS call
Patch-mainline: v4.14-rc4
Git-commit: ce024f42c2e28b6bce4ecc1e891b42f57f753892
References: bsc#1056787

When RTM_GETSTATS was added the fields of its header struct were not all
initialized when returning the result thus leaking 4 bytes of information
to user-space per rtnl_fill_statsinfo call, so initialize them now. Thanks
to Alexander Potapenko for the detailed report and bisection.

Reported-by: Alexander Potapenko <glider@google.com>
Fixes: 10c9ead9f3c6 ("rtnetlink: add new RTM_GETSTATS message to dump link stats")
Signed-off-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
Acked-by: Roopa Prabhu <roopa@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 net/core/rtnetlink.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -3865,6 +3865,9 @@ static int rtnl_fill_statsinfo(struct sk
 		return -EMSGSIZE;
 
 	ifsm = nlmsg_data(nlh);
+	ifsm->family = PF_UNSPEC;
+	ifsm->pad1 = 0;
+	ifsm->pad2 = 0;
 	ifsm->ifindex = dev->ifindex;
 	ifsm->filter_mask = filter_mask;