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From 1c3a5e72b70bcfaf342075a3fa5fcbdf99302a3f Mon Sep 17 00:00:00 2001
Message-Id: <1c3a5e72b70bcfaf342075a3fa5fcbdf99302a3f.1514245012.git.jan.steffens@gmail.com>
In-Reply-To: <b0bfa7c33cead5dd87267cfd4c29fda47dc1adc4.1514245012.git.jan.steffens@gmail.com>
References: <b0bfa7c33cead5dd87267cfd4c29fda47dc1adc4.1514245012.git.jan.steffens@gmail.com>
From: Steffen Klassert <steffen.klassert@secunet.com>
Date: Fri, 22 Dec 2017 10:44:57 +0100
Subject: [PATCH 2/3] xfrm: Fix stack-out-of-bounds read on socket policy
lookup.
When we do tunnel or beet mode, we pass saddr and daddr from the
template to xfrm_state_find(), this is ok. On transport mode,
we pass the addresses from the flowi, assuming that the IP
addresses (and address family) don't change during transformation.
This assumption is wrong in the IPv4 mapped IPv6 case, packet
is IPv4 and template is IPv6.
Fix this by catching address family missmatches of the policy
and the flow already before we do the lookup.
Reported-by: syzbot <syzkaller@googlegroups.com>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
---
net/xfrm/xfrm_policy.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c
index a2e531bf4f976308..c79ed3bed5d4dc2f 100644
--- a/net/xfrm/xfrm_policy.c
+++ b/net/xfrm/xfrm_policy.c
@@ -1169,9 +1169,15 @@ static struct xfrm_policy *xfrm_sk_policy_lookup(const struct sock *sk, int dir,
again:
pol = rcu_dereference(sk->sk_policy[dir]);
if (pol != NULL) {
- bool match = xfrm_selector_match(&pol->selector, fl, family);
+ bool match;
int err = 0;
+ if (pol->family != family) {
+ pol = NULL;
+ goto out;
+ }
+
+ match = xfrm_selector_match(&pol->selector, fl, family);
if (match) {
if ((sk->sk_mark & pol->mark.m) != pol->mark.v) {
pol = NULL;
--
2.15.1
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