From: Robert Shearman <rshearma@brocade.com>
Date: Fri, 6 Mar 2015 10:47:00 +0000 (+0000)
Subject: mpls: Properly validate RTA_VIA payload length
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=f8d54afc4c7a4c41deaa43fbcfffc2976094d342;p=GitHub%2Fmoto-9609%2Fandroid_kernel_motorola_exynos9610.git

mpls: Properly validate RTA_VIA payload length

If the nla length is less than 2 then the nla data could be accessed
beyond the accessible bounds. So ensure that the nla is big enough to
at least read the via_family before doing so. Replace magic value of
2.

Fixes: 03c0566542f4 ("mpls: Basic support for adding and removing routes")
Cc: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Robert Shearman <rshearma@brocade.com>
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---

diff --git a/net/mpls/af_mpls.c b/net/mpls/af_mpls.c
index 20cf48a8593d..4f265c677eca 100644
--- a/net/mpls/af_mpls.c
+++ b/net/mpls/af_mpls.c
@@ -586,8 +586,11 @@ static int rtm_to_route_config(struct sk_buff *skb,  struct nlmsghdr *nlh,
 		case RTA_VIA:
 		{
 			struct rtvia *via = nla_data(nla);
+			if (nla_len(nla) < offsetof(struct rtvia, rtvia_addr))
+				goto errout;
 			cfg->rc_via_family = via->rtvia_family;
-			cfg->rc_via_alen   = nla_len(nla) - 2;
+			cfg->rc_via_alen   = nla_len(nla) -
+				offsetof(struct rtvia, rtvia_addr);
 			if (cfg->rc_via_alen > MAX_VIA_ALEN)
 				goto errout;