From patchwork Mon Jul 9 17:19:03 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Pablo Neira Ayuso X-Patchwork-Id: 941484 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming-netdev@ozlabs.org Delivered-To: patchwork-incoming-netdev@ozlabs.org Authentication-Results: ozlabs.org; spf=none (mailfrom) smtp.mailfrom=vger.kernel.org (client-ip=209.132.180.67; helo=vger.kernel.org; envelope-from=netdev-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=none (p=none dis=none) header.from=netfilter.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 41PXBr2rj9z9s00 for ; Tue, 10 Jul 2018 03:19:48 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933771AbeGIRTS (ORCPT ); Mon, 9 Jul 2018 13:19:18 -0400 Received: from mail.us.es ([193.147.175.20]:41526 "EHLO mail.us.es" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933740AbeGIRTP (ORCPT ); Mon, 9 Jul 2018 13:19:15 -0400 Received: from antivirus1-rhel7.int (unknown [192.168.2.11]) by mail.us.es (Postfix) with ESMTP id DEC81E34F7 for ; Mon, 9 Jul 2018 19:17:27 +0200 (CEST) Received: from antivirus1-rhel7.int (localhost [127.0.0.1]) by antivirus1-rhel7.int (Postfix) with ESMTP id C8D08DA817 for ; Mon, 9 Jul 2018 19:17:27 +0200 (CEST) Received: by antivirus1-rhel7.int (Postfix, from userid 99) id C7459DA80C; Mon, 9 Jul 2018 19:17:27 +0200 (CEST) X-Spam-Checker-Version: SpamAssassin 3.4.1 (2015-04-28) on antivirus1-rhel7.int X-Spam-Level: X-Spam-Status: No, score=-108.2 required=7.5 tests=ALL_TRUSTED,BAYES_50, SMTPAUTH_US2,USER_IN_WHITELIST autolearn=disabled version=3.4.1 Received: from antivirus1-rhel7.int (localhost [127.0.0.1]) by antivirus1-rhel7.int (Postfix) with ESMTP id 797C2DA4C1; Mon, 9 Jul 2018 19:17:25 +0200 (CEST) Received: from 192.168.1.97 (192.168.1.97) by antivirus1-rhel7.int (F-Secure/fsigk_smtp/550/antivirus1-rhel7.int); Mon, 09 Jul 2018 19:17:25 +0200 (CEST) X-Virus-Status: clean(F-Secure/fsigk_smtp/550/antivirus1-rhel7.int) Received: from salvia.here (sys.soleta.eu [212.170.55.40]) (Authenticated sender: pneira@us.es) by entrada.int (Postfix) with ESMTPA id 4B8E14265A4E; Mon, 9 Jul 2018 19:17:25 +0200 (CEST) X-SMTPAUTHUS: auth mail.us.es From: Pablo Neira Ayuso To: netfilter-devel@vger.kernel.org Cc: davem@davemloft.net, netdev@vger.kernel.org Subject: [PATCH 5/6] netfilter: nf_conntrack: Fix possible possible crash on module loading. Date: Mon, 9 Jul 2018 19:19:03 +0200 Message-Id: <20180709171904.2460-6-pablo@netfilter.org> X-Mailer: git-send-email 2.11.0 In-Reply-To: <20180709171904.2460-1-pablo@netfilter.org> References: <20180709171904.2460-1-pablo@netfilter.org> X-Virus-Scanned: ClamAV using ClamSMTP Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org From: Andrey Ryabinin Loading the nf_conntrack module with doubled hashsize parameter, i.e. modprobe nf_conntrack hashsize=12345 hashsize=12345 causes NULL-ptr deref. If 'hashsize' specified twice, the nf_conntrack_set_hashsize() function will be called also twice. The first nf_conntrack_set_hashsize() call will set the 'nf_conntrack_htable_size' variable: nf_conntrack_set_hashsize() ... /* On boot, we can set this without any fancy locking. */ if (!nf_conntrack_htable_size) return param_set_uint(val, kp); But on the second invocation, the nf_conntrack_htable_size is already set, so the nf_conntrack_set_hashsize() will take a different path and call the nf_conntrack_hash_resize() function. Which will crash on the attempt to dereference 'nf_conntrack_hash' pointer: BUG: unable to handle kernel NULL pointer dereference at 0000000000000000 RIP: 0010:nf_conntrack_hash_resize+0x255/0x490 [nf_conntrack] Call Trace: nf_conntrack_set_hashsize+0xcd/0x100 [nf_conntrack] parse_args+0x1f9/0x5a0 load_module+0x1281/0x1a50 __se_sys_finit_module+0xbe/0xf0 do_syscall_64+0x7c/0x390 entry_SYSCALL_64_after_hwframe+0x49/0xbe Fix this, by checking !nf_conntrack_hash instead of !nf_conntrack_htable_size. nf_conntrack_hash will be initialized only after the module loaded, so the second invocation of the nf_conntrack_set_hashsize() won't crash, it will just reinitialize nf_conntrack_htable_size again. Signed-off-by: Andrey Ryabinin Signed-off-by: Pablo Neira Ayuso --- net/netfilter/nf_conntrack_core.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c index 3465da2a98bd..3d5280425027 100644 --- a/net/netfilter/nf_conntrack_core.c +++ b/net/netfilter/nf_conntrack_core.c @@ -2043,7 +2043,7 @@ int nf_conntrack_set_hashsize(const char *val, const struct kernel_param *kp) return -EOPNOTSUPP; /* On boot, we can set this without any fancy locking. */ - if (!nf_conntrack_htable_size) + if (!nf_conntrack_hash) return param_set_uint(val, kp); rc = kstrtouint(val, 0, &hashsize);