xfrm: Fix unlink race when policies are deleted.
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>
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 @@
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]--;