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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: 6ac098b2a9 ("xfrm: policy: add 2nd-level saddr trees for inexact policies")
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
This commit is contained in:
Florian Westphal 2019-01-04 14:17:05 +01:00 committed by Steffen Klassert
parent fcf86f55f2
commit 12750abad5
2 changed files with 9 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

15
net/xfrm/xfrm_policy.c
View File

@ -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;
}
}

4
tools/testing/selftests/net/xfrm_policy.sh
View File

@ -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.