From patchwork Wed Jul 3 22:33:04 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Pablo Neira Ayuso X-Patchwork-Id: 13722944 X-Patchwork-Delegate: kuba@kernel.org Received: from mail.netfilter.org (mail.netfilter.org [217.70.188.207]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 8EEAC191F80; Wed, 3 Jul 2024 22:33:21 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.70.188.207 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1720046003; cv=none; b=TOZ0BoHMiCxO4l46URmFU96/1OIJBexnO6D7xvJzw59lzP3hUB7f5Mk2xMdL0+C+7lFHrVJ/qLhR/oH7sKLc/BEkYU6kPb3gGER04lEh8mGwb1dmC3EysZQdoVjYmcoEsHAtIj4YifkFCaCbLJktRwelZTla+K0IoQKg2gtACzc= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1720046003; c=relaxed/simple; bh=n4g3BYjzp2KjDlb6miScUM14X5byqZbF5D/nbWh7wLs=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=qwrS7mmt/xZ7syOn7H9KAgB7DbqYxPl5QQlk7jVu3EzqRDzNkLyTHrNJPA+4LUEJBIgQsHkOrRffaedqqAGRs2qMI0YLZG9GOHCycswk/mKDA5UVoVXNGzEJNW46TtxAZJoMAZqquDsCgomMFSdaNnxYNmp5WaAHP/Hs+mSX910= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=netfilter.org; spf=pass smtp.mailfrom=netfilter.org; arc=none smtp.client-ip=217.70.188.207 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=netfilter.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=netfilter.org From: Pablo Neira Ayuso To: netfilter-devel@vger.kernel.org Cc: davem@davemloft.net, netdev@vger.kernel.org, kuba@kernel.org, pabeni@redhat.com, edumazet@google.com, fw@strlen.de Subject: [PATCH net 1/1] netfilter: nf_tables: unconditionally flush pending work before notifier Date: Thu, 4 Jul 2024 00:33:04 +0200 Message-Id: <20240703223304.1455-2-pablo@netfilter.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20240703223304.1455-1-pablo@netfilter.org> References: <20240703223304.1455-1-pablo@netfilter.org> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Patchwork-Delegate: kuba@kernel.org From: Florian Westphal syzbot reports: KASAN: slab-uaf in nft_ctx_update include/net/netfilter/nf_tables.h:1831 KASAN: slab-uaf in nft_commit_release net/netfilter/nf_tables_api.c:9530 KASAN: slab-uaf int nf_tables_trans_destroy_work+0x152b/0x1750 net/netfilter/nf_tables_api.c:9597 Read of size 2 at addr ffff88802b0051c4 by task kworker/1:1/45 [..] Workqueue: events nf_tables_trans_destroy_work Call Trace: nft_ctx_update include/net/netfilter/nf_tables.h:1831 [inline] nft_commit_release net/netfilter/nf_tables_api.c:9530 [inline] nf_tables_trans_destroy_work+0x152b/0x1750 net/netfilter/nf_tables_api.c:9597 Problem is that the notifier does a conditional flush, but its possible that the table-to-be-removed is still referenced by transactions being processed by the worker, so we need to flush unconditionally. We could make the flush_work depend on whether we found a table to delete in nf-next to avoid the flush for most cases. AFAICS this problem is only exposed in nf-next, with commit e169285f8c56 ("netfilter: nf_tables: do not store nft_ctx in transaction objects"), with this commit applied there is an unconditional fetch of table->family which is whats triggering the above splat. Fixes: 2c9f0293280e ("netfilter: nf_tables: flush pending destroy work before netlink notifier") Reported-and-tested-by: syzbot+4fd66a69358fc15ae2ad@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=4fd66a69358fc15ae2ad Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso --- net/netfilter/nf_tables_api.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c index e8dcf41d360d..081c08536d0f 100644 --- a/net/netfilter/nf_tables_api.c +++ b/net/netfilter/nf_tables_api.c @@ -11483,8 +11483,7 @@ static int nft_rcv_nl_event(struct notifier_block *this, unsigned long event, gc_seq = nft_gc_seq_begin(nft_net); - if (!list_empty(&nf_tables_destroy_list)) - nf_tables_trans_destroy_flush_work(); + nf_tables_trans_destroy_flush_work(); again: list_for_each_entry(table, &nft_net->tables, list) { if (nft_table_has_owner(table) &&