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 3C066C32793 for ; Tue, 23 Aug 2022 23:39:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232007AbiHWXjf (ORCPT ); Tue, 23 Aug 2022 19:39:35 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41328 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229445AbiHWXjd (ORCPT ); Tue, 23 Aug 2022 19:39:33 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E444C89CFA for ; Tue, 23 Aug 2022 16:39:32 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 7F0DD616BE for ; Tue, 23 Aug 2022 23:39:32 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id A8807C433D6; Tue, 23 Aug 2022 23:39:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1661297971; bh=1GZOnSVNyb2xRN1ldhJ5eq2dsXlLoocROv6iRlgcKa4=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=VP6dohBa05h57O/QlO1PgdHvaf4MJnKWC+iL0AwsIpSGnPMyFt9pav5yJnxvYdIUf ihPWhebL0+rkUpCdYoLk/UJUlR6MBIcDsecEhOSLp8SbbyathfovDivsAul1OUfasP OyTjIfF8dUiq0MBpFt0LKUrorBtyhL70/yYZ4ST9GZ/KNGI++/Coi4wFI5cxS1hJnA Me9iqOqWeDi2HSo9NDZnH7zIUFvqdC3HoYpHw2351ziDnqJ6TzHosHDDGhAaMYL53D TiIHyKsyZ3Yt5Gm/QhcH/AYVXeDQNK+Capw294kpXy9yhY4Ee+xpKiibwJVAF/Jz7B BVrnRCiBmNcAw== Date: Tue, 23 Aug 2022 16:39:30 -0700 From: Jakub Kicinski To: Cong Wang Cc: netdev@vger.kernel.org, Cong Wang , syzbot+9fc084a4348493ef65d2@syzkaller.appspotmail.com, syzbot+e696806ef96cdd2d87cd@syzkaller.appspotmail.com, Tom Herbert Subject: Re: [Patch net] kcm: get rid of unnecessary cleanup Message-ID: <20220823163930.033b1330@kernel.org> In-Reply-To: <20220822040628.177649-1-xiyou.wangcong@gmail.com> References: <20220822040628.177649-1-xiyou.wangcong@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Sun, 21 Aug 2022 21:06:28 -0700 Cong Wang wrote: > From: Cong Wang > > strp_init() is called just a few lines above this csk->sk_user_data > check, it also initializes strp->work etc., therefore, it is > unnecessary to call strp_done() to cancel the freshly initialized > work. > > This also makes a lockdep warning reported by syzbot go away. > > Reported-and-tested-by: syzbot+9fc084a4348493ef65d2@syzkaller.appspotmail.com > Reported-by: syzbot+e696806ef96cdd2d87cd@syzkaller.appspotmail.com > Fixes: e5571240236c ("kcm: Check if sk_user_data already set in kcm_attach") > Fixes: dff8baa26117 ("kcm: Call strp_stop before strp_done in kcm_attach") > Cc: Jakub Kicinski > Cc: Tom Herbert > Signed-off-by: Cong Wang > --- > net/kcm/kcmsock.c | 2 -- > 1 file changed, 2 deletions(-) > > diff --git a/net/kcm/kcmsock.c b/net/kcm/kcmsock.c > index 71899e5a5a11..661c40cdab3e 100644 > --- a/net/kcm/kcmsock.c > +++ b/net/kcm/kcmsock.c > @@ -1425,8 +1425,6 @@ static int kcm_attach(struct socket *sock, struct socket *csock, > */ > if (csk->sk_user_data) { > write_unlock_bh(&csk->sk_callback_lock); > - strp_stop(&psock->strp); > - strp_done(&psock->strp); > kmem_cache_free(kcm_psockp, psock); > err = -EALREADY; > goto out; Looks correct, but if strp_init() ever grows code which needs to be unwound in strp_done() we'd risk a leak. This seems to have been Tom's intent. Could we perhaps reorder the sk_user_data check vs the strp_init() call? sock_map already calls strp_init() under the callback lock so we'd not be introducing any new lock ordering.