From bdddbf6996c0b9299efc97b8f66e06286f3aa8c9 Mon Sep 17 00:00:00 2001
From: Li RongQing <roy.qing.li@gmail.com>
Date: Wed, 29 Apr 2015 08:42:44 +0800
Subject: [PATCH] xfrm: fix a race in xfrm_state_lookup_byspi

The returned xfrm_state should be hold before unlock xfrm_state_lock,
otherwise the returned xfrm_state maybe be released.

Fixes: c454997e6[{pktgen, xfrm} Introduce xfrm_state_lookup_byspi..]
Cc: Fan Du <fan.du@intel.com>
Signed-off-by: Li RongQing <roy.qing.li@gmail.com>
Acked-by: Fan Du <fan.du@intel.com>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
---
 net/xfrm/xfrm_state.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/xfrm/xfrm_state.c b/net/xfrm/xfrm_state.c
index f5e39e35d73a..96688cd0f6f1 100644
--- a/net/xfrm/xfrm_state.c
+++ b/net/xfrm/xfrm_state.c
@@ -927,8 +927,8 @@ struct xfrm_state *xfrm_state_lookup_byspi(struct net *net, __be32 spi,
 			x->id.spi != spi)
 			continue;
 
-		spin_unlock_bh(&net->xfrm.xfrm_state_lock);
 		xfrm_state_hold(x);
+		spin_unlock_bh(&net->xfrm.xfrm_state_lock);
 		return x;
 	}
 	spin_unlock_bh(&net->xfrm.xfrm_state_lock);