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Commit 12750aba authored by Florian Westphal's avatar Florian Westphal Committed by Steffen Klassert
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xfrm: policy: fix infinite loop when merging src-nodes 



With very small change to test script we can trigger softlockup due to
bogus assignment of 'p' (policy to be examined) on restart.

Previously the two to-be-merged nodes had same address/prefixlength pair,
so no erase/reinsert was necessary, we only had to append the list from
node a to b.

If prefix lengths are different, the node has to be deleted and re-inserted
into the tree, with the updated prefix length.  This was broken; due to
bogus update to 'p' this loops forever.

Add a 'restart' label and use that instead.

While at it, don't perform the unneeded reinserts of the policies that
are already sorted into the 'new' node.

A previous patch in this series made xfrm_policy_inexact_list_reinsert()
use the relative position indicator to sort policies according to age in
case priorities are identical.

Fixes: 6ac098b2 ("xfrm: policy: add 2nd-level saddr trees for inexact policies")
Signed-off-by: default avatarFlorian Westphal <fw@strlen.de>
Signed-off-by: default avatarSteffen Klassert <steffen.klassert@secunet.com>
parent fcf86f55

net/xfrm/xfrm_policy.c

+7 −8
Original line number Diff line number Diff line
@@ -886,12 +886,13 @@ static void xfrm_policy_inexact_node_reinsert(struct net *net, 
					      struct rb_root *new,

					      u16 family)

{

	struct rb_node **p, *parent = NULL;

	struct xfrm_pol_inexact_node *node;

	struct rb_node **p, *parent;



	/* we should not have another subtree here */

	WARN_ON_ONCE(!RB_EMPTY_ROOT(&n->root));



restart:

	parent = NULL;

	p = &new->rb_node;

	while (*p) {

		u8 prefixlen;
@@ -911,12 +912,11 @@ static void xfrm_policy_inexact_node_reinsert(struct net *net, 
		} else {

			struct xfrm_policy *tmp;



			hlist_for_each_entry(tmp, &node->hhead, bydst)

				tmp->bydst_reinsert = true;

			hlist_for_each_entry(tmp, &n->hhead, bydst)

			hlist_for_each_entry(tmp, &n->hhead, bydst) {

				tmp->bydst_reinsert = true;

				hlist_del_rcu(&tmp->bydst);

			}



			INIT_HLIST_HEAD(&node->hhead);

			xfrm_policy_inexact_list_reinsert(net, node, family);



			if (node->prefixlen == n->prefixlen) {
@@ -928,8 +928,7 @@ static void xfrm_policy_inexact_node_reinsert(struct net *net, 
			kfree_rcu(n, rcu);

			n = node;

			n->prefixlen = prefixlen;

			*p = new->rb_node;

			parent = NULL;

			goto restart;

		}

	}

tools/testing/selftests/net/xfrm_policy.sh

+2 −2
Original line number Diff line number Diff line
@@ -78,8 +78,8 @@ do_overlap() 
    # adds a new node in the 10.0.0.0/24 tree (dst node exists).

    ip -net $ns xfrm policy add src 10.2.0.0/24 dst 10.0.0.0/24 dir fwd priority 200 action block



    # adds a 10.2.0.0/24 node, but for different dst.

    ip -net $ns xfrm policy add src 10.2.0.0/24 dst 10.0.1.0/24 dir fwd priority 200 action block

    # adds a 10.2.0.0/23 node, but for different dst.

    ip -net $ns xfrm policy add src 10.2.0.0/23 dst 10.0.1.0/24 dir fwd priority 200 action block



    # dst now overlaps with the 10.0.1.0/24 ESP policy in fwd.

    # kernel must 'promote' existing one (10.0.0.0/24) to 10.0.0.0/23.