[PATCH net v2 1/3] xfrm: Fix xfrm_input() to verify state is valid when (encap_type < 0)

[avivh]

From: Aviv Heller <av...@mellanox.com>

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 <av...@mellanox.com>
Signed-off-by: Yevgeny Kliteynik <klit...@mellanox.com>
---
 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 347ab31..da64473 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. */
-- 
1.8.3.1