[XFRM]: Fix ordering issue in xfrm_dst_hash_transfer().

Keep ordering of policy entries with same selector in
xfrm_dst_hash_transfer().

Issue should not appear in usual cases because multiple policy entries
with same selector are basically not allowed so far.  Bug was pointed
out by Sebastien Decugis <sdecugis@hongo.wide.ad.jp>.

We could convert bydst from hlist to list and use list_add_tail()
instead.

Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Acked-by: Sebastien Decugis <sdecugis@hongo.wide.ad.jp>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 18 insertions, 2 deletions

diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c
index 47219f98053f..9fc4c315f6cd 100644
--- a/net/xfrm/xfrm_policy.c
+++ b/net/xfrm/xfrm_policy.c
@@ -331,15 +331,31 @@ static void xfrm_dst_hash_transfer(struct hlist_head *list,
                                    struct hlist_head *ndsttable,
                                    unsigned int nhashmask)
 {
-        struct hlist_node *entry, *tmp;
+        struct hlist_node *entry, *tmp, *entry0 = NULL;
         struct xfrm_policy *pol;
+        unsigned int h0 = 0;
 
+redo:
         hlist_for_each_entry_safe(pol, entry, tmp, list, bydst) {
                 unsigned int h;
 
                 h = __addr_hash(&pol->selector.daddr, &pol->selector.saddr,
                                 pol->family, nhashmask);
-                hlist_add_head(&pol->bydst, ndsttable+h);
+                if (!entry0) {
+                        hlist_del(entry);
+                        hlist_add_head(&pol->bydst, ndsttable+h);
+                        h0 = h;
+                } else {
+                        if (h != h0)
+                                continue;
+                        hlist_del(entry);
+                        hlist_add_after(entry0, &pol->bydst);
+                }
+                entry0 = entry;
+        }
+        if (!hlist_empty(list)) {
+                entry0 = NULL;
+                goto redo;
         }
 }