From 3ea55a3fa7cb5b5a0483b9452d8dc7de5e232f72 Mon Sep 17 00:00:00 2001 From: Pablo Neira Ayuso Date: Mon, 21 Aug 2023 13:24:37 +0200 Subject: [PATCH -stable,4.19 08/20] netfilter: nft_set_rbtree: fix overlap expiration walk commit f718863aca469a109895cb855e6b81fff4827d71 upstream. The lazy gc on insert that should remove timed-out entries fails to release the other half of the interval, if any. Can be reproduced with tests/shell/testcases/sets/0044interval_overlap_0 in nftables.git and kmemleak enabled kernel. Second bug is the use of rbe_prev vs. prev pointer. If rbe_prev() returns NULL after at least one iteration, rbe_prev points to element that is not an end interval, hence it should not be removed. Lastly, check the genmask of the end interval if this is active in the current generation. Fixes: c9e6978e2725 ("netfilter: nft_set_rbtree: Switch to node list walk for overlap detection") Signed-off-by: Florian Westphal Signed-off-by: Sasha Levin --- net/netfilter/nft_set_rbtree.c | 20 ++++++++++++++------ 1 file changed, 14 insertions(+), 6 deletions(-) diff --git a/net/netfilter/nft_set_rbtree.c b/net/netfilter/nft_set_rbtree.c index dc37a8b29f43..14eefd24472c 100644 --- a/net/netfilter/nft_set_rbtree.c +++ b/net/netfilter/nft_set_rbtree.c @@ -219,29 +219,37 @@ static void *nft_rbtree_get(const struct net *net, const struct nft_set *set, static int nft_rbtree_gc_elem(const struct nft_set *__set, struct nft_rbtree *priv, - struct nft_rbtree_elem *rbe) + struct nft_rbtree_elem *rbe, + u8 genmask) { struct nft_set *set = (struct nft_set *)__set; struct rb_node *prev = rb_prev(&rbe->node); - struct nft_rbtree_elem *rbe_prev = NULL; + struct nft_rbtree_elem *rbe_prev; struct nft_set_gc_batch *gcb; gcb = nft_set_gc_batch_check(set, NULL, GFP_ATOMIC); if (!gcb) return -ENOMEM; - /* search for expired end interval coming before this element. */ + /* search for end interval coming before this element. + * end intervals don't carry a timeout extension, they + * are coupled with the interval start element. + */ while (prev) { rbe_prev = rb_entry(prev, struct nft_rbtree_elem, node); - if (nft_rbtree_interval_end(rbe_prev)) + if (nft_rbtree_interval_end(rbe_prev) && + nft_set_elem_active(&rbe_prev->ext, genmask)) break; prev = rb_prev(prev); } - if (rbe_prev) { + if (prev) { + rbe_prev = rb_entry(prev, struct nft_rbtree_elem, node); + rb_erase(&rbe_prev->node, &priv->root); atomic_dec(&set->nelems); + nft_set_gc_batch_add(gcb, rbe_prev); } rb_erase(&rbe->node, &priv->root); @@ -323,7 +331,7 @@ static int __nft_rbtree_insert(const struct net *net, const struct nft_set *set, /* perform garbage collection to avoid bogus overlap reports. */ if (nft_set_elem_expired(&rbe->ext)) { - err = nft_rbtree_gc_elem(set, priv, rbe); + err = nft_rbtree_gc_elem(set, priv, rbe, genmask); if (err < 0) return err; -- 2.30.2