netfilter: nft_set_rbtree: overlap detection with element re-addition after deletion

This patch fixes spurious EEXIST errors.

Extend d2df92e9 ("netfilter: nft_set_rbtree: handle element
re-addition after deletion") to deal with elements with same end flags
in the same transation.

Reset the overlap flag as described by 7c84d414 ("netfilter:
nft_set_rbtree: Detect partial overlaps on insertion").

Fixes: 7c84d414 ("netfilter: nft_set_rbtree: Detect partial overlaps on insertion")
Fixes: d2df92e9 ("netfilter: nft_set_rbtree: handle element re-addition after deletion")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Reviewed-by: Stefano Brivio <sbrivio@redhat.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

net/netfilter/nft_set_rbtree.c

@@ -349,7 +349,11 @@ static int __nft_rbtree_insert(const struct net *net, const struct nft_set *set,
 				*ext = &rbe->ext;
 				return -EEXIST;
 			} else {
-				p = &parent->rb_left;
+				overlap = false;
+				if (nft_rbtree_interval_end(rbe))
+					p = &parent->rb_left;
+				else
+					p = &parent->rb_right;
 			}
 		}