[PATCH 5/5] xfrm: Fix unlink race when policies are deleted.

[Steffen Klassert <steffen.klassert@secunet.com>]

When a policy is unlinked from the lists in thread context,
the xfrm timer can fire before we can mark this policy as dead.
So reinitialize the bydst hlist, then hlist_unhashed() will
notice that this policy is not linked and will avoid a
doulble unlink of that policy.

Reported-by: Xianpeng Zhao <673321875@qq.com>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
---
 net/xfrm/xfrm_policy.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c
index 4b98b25..1d5c7bf 100644
--- a/net/xfrm/xfrm_policy.c
+++ b/net/xfrm/xfrm_policy.c
@@ -1158,7 +1158,7 @@ static struct xfrm_policy *__xfrm_policy_unlink(struct xfrm_policy *pol,
 	if (hlist_unhashed(&pol->bydst))
 		return NULL;
 
-	hlist_del(&pol->bydst);
+	hlist_del_init(&pol->bydst);
 	hlist_del(&pol->byidx);
 	list_del(&pol->walk.all);
 	net->xfrm.policy_count[dir]--;
-- 
1.7.9.5