From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 79C79C433F5 for ; Mon, 21 Feb 2022 11:19:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1355799AbiBULT2 (ORCPT ); Mon, 21 Feb 2022 06:19:28 -0500 Received: from mxb-00190b01.gslb.pphosted.com ([23.128.96.19]:48130 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1345189AbiBULRk (ORCPT ); Mon, 21 Feb 2022 06:17:40 -0500 Received: from Chamillionaire.breakpoint.cc (Chamillionaire.breakpoint.cc [IPv6:2a0a:51c0:0:12e:520::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id ADADB1409D for ; Mon, 21 Feb 2022 02:59:24 -0800 (PST) Received: from fw by Chamillionaire.breakpoint.cc with local (Exim 4.92) (envelope-from ) id 1nM6Pa-0000Nr-Ks; Mon, 21 Feb 2022 11:59:22 +0100 Date: Mon, 21 Feb 2022 11:59:22 +0100 From: Florian Westphal To: Florian Westphal Cc: Pablo Neira Ayuso , netfilter-devel@vger.kernel.org, Fernando Fernandez Mancera Subject: Re: [PATCH v2 nf] netfilter: nf_tables: fix memory leak during stateful obj update Message-ID: <20220221105922.GC18967@breakpoint.cc> References: <20220220111850.87378-1-fw@strlen.de> <20220221104635.GB18967@breakpoint.cc> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220221104635.GB18967@breakpoint.cc> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: netfilter-devel@vger.kernel.org Florian Westphal wrote: > Pablo Neira Ayuso wrote: > > On Sun, Feb 20, 2022 at 12:18:50PM +0100, Florian Westphal wrote: > > > stateful objects can be updated from the control plane. > > > The transaction logic allocates a temporary object for this purpose. > > > > > > This object has to be released via nft_obj_destroy, not kfree, since > > > the ->init function was called and it can have side effects beyond > > > memory allocation. > > > > > > Unlike normal NEWOBJ path, the objects module refcount isn't > > > incremented, so add nft_newobj_destroy and use that. > > > > Probably this? .udata and .key is NULL for the update path so kfree > > should be fine. > > Yes, that works too. > > We could also ... > > > - module_put(obj->ops->type->owner); > > + /* nf_tables_updobj does not increment module refcount */ > > + if (!update) > > + module_put(obj->ops->type->owner); > > + > > Increment the refcount for update case as well to avoid the special > case? Untested: diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c index 3081c4399f10..49060f281342 100644 --- a/net/netfilter/nf_tables_api.c +++ b/net/netfilter/nf_tables_api.c @@ -6553,10 +6553,13 @@ static int nf_tables_updobj(const struct nft_ctx *ctx, struct nft_trans *trans; int err; + if (!try_module_get(type->owner)) + return -ENOENT; + trans = nft_trans_alloc(ctx, NFT_MSG_NEWOBJ, sizeof(struct nft_trans_obj)); if (!trans) - return -ENOMEM; + goto err_trans; newobj = nft_obj_init(ctx, type, attr); if (IS_ERR(newobj)) { @@ -6573,6 +6576,8 @@ static int nf_tables_updobj(const struct nft_ctx *ctx, err_free_trans: kfree(trans); +err_trans: + module_put(type->owner); return err; } @@ -8185,7 +8190,7 @@ static void nft_obj_commit_update(struct nft_trans *trans) if (obj->ops->update) obj->ops->update(obj, newobj); - kfree(newobj); + nft_obj_destroy(&trans->ctx, newobj); } static void nft_commit_release(struct nft_trans *trans) @@ -8976,7 +8981,7 @@ static int __nf_tables_abort(struct net *net, enum nfnl_abort_action action) break; case NFT_MSG_NEWOBJ: if (nft_trans_obj_update(trans)) { - kfree(nft_trans_obj_newobj(trans)); + nft_obj_destroy(&trans->ctx, nft_trans_obj_newobj(trans)); nft_trans_destroy(trans); } else { trans->ctx.table->use--;