Patch "netfilter: nat: fix src map lookup" has been added to the 4.9-stable tree

This is a note to let you know that I've just added the patch titled

netfilter: nat: fix src map lookup

to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
netfilter-nat-fix-src-map-lookup.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Florian Westphal <[email protected]>
Date: Fri, 7 Jul 2017 13:07:17 +0200
Subject: netfilter: nat: fix src map lookup

From: Florian Westphal <[email protected]>

commit 97772bcd56efa21d9d8976db6f205574ea602f51 upstream.

When doing initial conversion to rhashtable I replaced the bucket walk with a single rhashtable_lookup_fast().

When moving to rhlist I failed to properly walk the list of identical tuples, but that is what is needed for this to work correctly. The table contains the original tuples, so the reply tuples are all distinct.

We currently decide that mapping is (not) in range only based on the first entry, but in case its not we need to try the reply tuple of the next entry until we either find an in-range mapping or we checked all the entries.

This bug makes nat core attempt collision resolution while it might be able to use the mapping as-is.

---
 net/netfilter/nf_nat_core.c |   17 +++++++++--------
 1 file changed, 9 insertions(+), 8 deletions(-)

@@ -225,20 +225,21 @@ find_appropriate_src(struct net *net,
 		.tuple = tuple,
 		.zone = zone
 	};
-	struct rhlist_head *hl;
+	struct rhlist_head *hl, *h;
 
 	hl = rhltable_lookup(&nf_nat_bysource_table, &key,
 			     nf_nat_bysource_params);
-	if (!hl)
-		return 0;
 
-	ct = container_of(hl, typeof(*ct), nat_bysource);
+	rhl_for_each_entry_rcu(ct, h, hl, nat_bysource) {
+		nf_ct_invert_tuplepr(result,
+				     &ct->tuplehash[IP_CT_DIR_REPLY].tuple);
+		result->dst = tuple->dst;
 
-	nf_ct_invert_tuplepr(result,
-			     &ct->tuplehash[IP_CT_DIR_REPLY].tuple);
-	result->dst = tuple->dst;
+		if (in_range(l3proto, l4proto, result, range))
+			return 1;
+	}
 
-	return in_range(l3proto, l4proto, result, range);
+	return 0;
 }
 
 /* For [FUTURE] fragmentation handling, we want the least-used

Patches currently in stable-queue which might be from [email protected] are

queue-4.9/netfilter-nat-fix-src-map-lookup.patch