From: Aviv Heller <avivh@mellanox.com>
Date: Tue, 28 Nov 2017 19:55:40 +0200
Subject: xfrm: Fix xfrm_input() to verify state is valid when (encap_type < 0)
Patch-mainline: v4.15-rc6
Git-commit: 4ce3dbe397d7b6b15f272ae757c78c35e9e4b61d
References: bsc#1076830

Code path when (encap_type < 0) does not verify the state is valid
before progressing.

This will result in a crash if, for instance, x->km.state ==
XFRM_STATE_ACQ.

Fixes: 7785bba299a8 ("esp: Add a software GRO codepath")
Signed-off-by: Aviv Heller <avivh@mellanox.com>
Signed-off-by: Yevgeny Kliteynik <kliteyn@mellanox.com>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Acked-by: Michal Kubecek <mkubecek@suse.cz>

---
 net/xfrm/xfrm_input.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/net/xfrm/xfrm_input.c b/net/xfrm/xfrm_input.c
index 9de4b1dbc0ae..f2f7ad03cc3d 100644
--- a/net/xfrm/xfrm_input.c
+++ b/net/xfrm/xfrm_input.c
@@ -206,7 +206,7 @@ int xfrm_input(struct sk_buff *skb, int nexthdr, __be32 spi, int encap_type)
 	xfrm_address_t *daddr;
 	struct xfrm_mode *inner_mode;
 	u32 mark = skb->mark;
-	unsigned int family;
+	unsigned int family = AF_UNSPEC;
 	int decaps = 0;
 	int async = 0;
 	bool xfrm_gro = false;
@@ -215,6 +215,16 @@ int xfrm_input(struct sk_buff *skb, int nexthdr, __be32 spi, int encap_type)
 
 	if (encap_type < 0) {
 		x = xfrm_input_state(skb);
+
+		if (unlikely(x->km.state != XFRM_STATE_VALID)) {
+			if (x->km.state == XFRM_STATE_ACQ)
+				XFRM_INC_STATS(net, LINUX_MIB_XFRMACQUIREERROR);
+			else
+				XFRM_INC_STATS(net,
+					       LINUX_MIB_XFRMINSTATEINVALID);
+			goto drop;
+		}
+
 		family = x->outer_mode->afinfo->family;
 
 		/* An encap_type of -1 indicates async resumption. */
-- 
2.15.1