[PATCH AUTOSEL for 4.14 076/100] xfrm: Fix xfrm_input() to verify state is valid when (encap_type < 0)

[Sasha Levin]

From: Aviv Heller <avivh@xxxxxxxxxxxx>

[ Upstream commit 4ce3dbe397d7b6b15f272ae757c78c35e9e4b61d ]

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@xxxxxxxxxxxx>
Signed-off-by: Yevgeny Kliteynik <kliteyn@xxxxxxxxxxxx>
Signed-off-by: Steffen Klassert <steffen.klassert@xxxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx>
---
 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 347ab31574d5..da6447389ffb 100644
--- a/net/xfrm/xfrm_input.c
+++ b/net/xfrm/xfrm_input.c
@@ -207,7 +207,7 @@ 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;
@@ -216,6 +216,16 @@ 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. */
-- 
2.11.0