linux-kernel - [PATCH 4.14 029/165] netfilter: nf_tables: fix memory leaks on chain rename

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Date:   Mon,  3 Sep 2018 18:55:15 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Florian Westphal <fw@...len.de>,
        Pablo Neira Ayuso <pablo@...filter.org>,
        Sasha Levin <alexander.levin@...rosoft.com>
Subject: [PATCH 4.14 029/165] netfilter: nf_tables: fix memory leaks on chain rename

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

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

From: Florian Westphal <fw@...len.de>

[ Upstream commit 9f8aac0be21ed5f99bd5ba0ff315d710737d1794 ]

The new name is stored in the transaction metadata, on commit,
the pointers to the old and new names are swapped.

Therefore in abort and commit case we have to free the
pointer in the chain_trans container.

In commit case, the pointer can be used by another cpu that
is currently dumping the renamed chain, thus kfree needs to
happen after waiting for rcu readers to complete.

Fixes: b7263e071a ("netfilter: nf_tables: Allow chain name of up to 255 chars")
Signed-off-by: Florian Westphal <fw@...len.de>
Signed-off-by: Pablo Neira Ayuso <pablo@...filter.org>
Signed-off-by: Sasha Levin <alexander.levin@...rosoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 net/netfilter/nf_tables_api.c |   17 +++++++++++------
 1 file changed, 11 insertions(+), 6 deletions(-)

--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -5043,6 +5043,9 @@ static void nf_tables_commit_release(str
 	case NFT_MSG_DELTABLE:
 		nf_tables_table_destroy(&trans->ctx);
 		break;
+	case NFT_MSG_NEWCHAIN:
+		kfree(nft_trans_chain_name(trans));
+		break;
 	case NFT_MSG_DELCHAIN:
 		nf_tables_chain_destroy(trans->ctx.chain);
 		break;
@@ -5100,13 +5103,15 @@ static int nf_tables_commit(struct net *
 			nf_tables_table_notify(&trans->ctx, NFT_MSG_DELTABLE);
 			break;
 		case NFT_MSG_NEWCHAIN:
-			if (nft_trans_chain_update(trans))
+			if (nft_trans_chain_update(trans)) {
 				nft_chain_commit_update(trans);
-			else
+				nf_tables_chain_notify(&trans->ctx, NFT_MSG_NEWCHAIN);
+				/* trans destroyed after rcu grace period */
+			} else {
 				nft_clear(net, trans->ctx.chain);
-
-			nf_tables_chain_notify(&trans->ctx, NFT_MSG_NEWCHAIN);
-			nft_trans_destroy(trans);
+				nf_tables_chain_notify(&trans->ctx, NFT_MSG_NEWCHAIN);
+				nft_trans_destroy(trans);
+			}
 			break;
 		case NFT_MSG_DELCHAIN:
 			list_del_rcu(&trans->ctx.chain->list);
@@ -5246,7 +5251,7 @@ static int nf_tables_abort(struct net *n
 		case NFT_MSG_NEWCHAIN:
 			if (nft_trans_chain_update(trans)) {
 				free_percpu(nft_trans_chain_stats(trans));
-
+				kfree(nft_trans_chain_name(trans));
 				nft_trans_destroy(trans);
 			} else {
 				trans->ctx.table->use--;