[PATCH 4.9 119/119] netfilter: nft_set_rbtree: handle element re-addition after deletion

[Greg Kroah-Hartman]

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx>

commit d2df92e98a34a5619dadd29c6291113c009181e7 upstream.

The existing code selects no next branch to be inspected when
re-inserting an inactive element into the rb-tree, looping endlessly.
This patch restricts the check for active elements to the EEXIST case
only.

Fixes: e701001e7cbe ("netfilter: nft_rbtree: allow adjacent intervals with dynamic updates")
Reported-by: Wolfgang Bumiller <w.bumiller@xxxxxxxxxxx>
Tested-by: Wolfgang Bumiller <w.bumiller@xxxxxxxxxxx>
Signed-off-by: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 net/netfilter/nft_set_rbtree.c |   22 +++++++++++-----------
 1 file changed, 11 insertions(+), 11 deletions(-)

--- a/net/netfilter/nft_set_rbtree.c
+++ b/net/netfilter/nft_set_rbtree.c
@@ -118,17 +118,17 @@ static int __nft_rbtree_insert(const str
 		else if (d > 0)
 			p = &parent->rb_right;
 		else {
-			if (nft_set_elem_active(&rbe->ext, genmask)) {
-				if (nft_rbtree_interval_end(rbe) &&
-				    !nft_rbtree_interval_end(new))
-					p = &parent->rb_left;
-				else if (!nft_rbtree_interval_end(rbe) &&
-					 nft_rbtree_interval_end(new))
-					p = &parent->rb_right;
-				else {
-					*ext = &rbe->ext;
-					return -EEXIST;
-				}
+			if (nft_rbtree_interval_end(rbe) &&
+			    !nft_rbtree_interval_end(new)) {
+				p = &parent->rb_left;
+			} else if (!nft_rbtree_interval_end(rbe) &&
+				   nft_rbtree_interval_end(new)) {
+				p = &parent->rb_right;
+			} else if (nft_set_elem_active(&rbe->ext, genmask)) {
+				*ext = &rbe->ext;
+				return -EEXIST;
+			} else {
+				p = &parent->rb_left;
 			}
 		}
 	}