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 25957ECAAD8 for ; Tue, 13 Sep 2022 17:50:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233553AbiIMRu5 (ORCPT ); Tue, 13 Sep 2022 13:50:57 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55494 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233588AbiIMRu1 (ORCPT ); Tue, 13 Sep 2022 13:50:27 -0400 Received: from pandora.armlinux.org.uk (pandora.armlinux.org.uk [IPv6:2001:4d48:ad52:32c8:5054:ff:fe00:142]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9D73583BEA; Tue, 13 Sep 2022 09:49:02 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=armlinux.org.uk; s=pandora-2019; h=Sender:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=NYivW7kGXMdzt9vJTehSUvSt+4w7RPSokt3xYSE0iuE=; b=mNLXbpbGexsGm7Dl3VPIIsQLR9 st3jg0j5fPR1VAeY+tHcbUE/gIALlzHoryZPRpi6q8xtCrkz3PxJMB4Z5QSaVsppUiJKPKV+2PYHR +BRZZutQnZd3T4wWxDrr2hN4jAjDgOewapVfbkFIdGZZfJXc8bWn2aAsWS2QwIrDS33hGZYXeKP4F 82VBugtGPqAOqPwk/PiCjsMkMPkQ9+adpF6Hw3b+3kbppxAUQBVZwMARpeZL5Agud/X5NVF05mbY3 Es7KG5sfg3k8T5pQ1AuMqtFxpAty+WU4r9CXPK9+SUfHlxfjrlWSzzTcwFeYYXPRPGFx9a8xhD0y+ yxZ9MM4A==; Received: from shell.armlinux.org.uk ([fd8f:7570:feb6:1:5054:ff:fe00:4ec]:34296) by pandora.armlinux.org.uk with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1oY95n-0003IX-FU; Tue, 13 Sep 2022 17:48:59 +0100 Received: from linux by shell.armlinux.org.uk with local (Exim 4.94.2) (envelope-from ) id 1oY95m-0000pK-3i; Tue, 13 Sep 2022 17:48:58 +0100 Date: Tue, 13 Sep 2022 17:48:58 +0100 From: "Russell King (Oracle)" To: Greg Kroah-Hartman Cc: linux-kernel@vger.kernel.org, stable@vger.kernel.org, Marcin Wojtas , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , netdev@vger.kernel.org, stable Subject: Re: [PATCH 5.19 005/192] net: mvpp2: debugfs: fix memory leak when using debugfs_lookup() Message-ID: References: <20220913140410.043243217@linuxfoundation.org> <20220913140410.277221532@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220913140410.277221532@linuxfoundation.org> Sender: Russell King (Oracle) Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Tue, Sep 13, 2022 at 04:01:51PM +0200, Greg Kroah-Hartman wrote: > From: Greg Kroah-Hartman > > commit fe2c9c61f668cde28dac2b188028c5299cedcc1e upstream. > > When calling debugfs_lookup() the result must have dput() called on it, > otherwise the memory will leak over time. Fix this up to be much > simpler logic and only create the root debugfs directory once when the > driver is first accessed. That resolves the memory leak and makes > things more obvious as to what the intent is. > > Cc: Marcin Wojtas > Cc: Russell King > Cc: "David S. Miller" > Cc: Eric Dumazet > Cc: Jakub Kicinski > Cc: Paolo Abeni > Cc: netdev@vger.kernel.org > Cc: stable > Fixes: 21da57a23125 ("net: mvpp2: add a debugfs interface for the Header Parser") > Signed-off-by: David S. Miller > Signed-off-by: Greg Kroah-Hartman > --- > drivers/net/ethernet/marvell/mvpp2/mvpp2_debugfs.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > --- a/drivers/net/ethernet/marvell/mvpp2/mvpp2_debugfs.c > +++ b/drivers/net/ethernet/marvell/mvpp2/mvpp2_debugfs.c > @@ -700,10 +700,10 @@ void mvpp2_dbgfs_cleanup(struct mvpp2 *p > > void mvpp2_dbgfs_init(struct mvpp2 *priv, const char *name) > { > - struct dentry *mvpp2_dir, *mvpp2_root; > + static struct dentry *mvpp2_root; > + struct dentry *mvpp2_dir; > int ret, i; > > - mvpp2_root = debugfs_lookup(MVPP2_DRIVER_NAME, NULL); > if (!mvpp2_root) > mvpp2_root = debugfs_create_dir(MVPP2_DRIVER_NAME, NULL); This looks broken to me. What happens if this is built as a module, and the module is loaded, binds (and creates the directory), then is removed, and then re- inserted? Nothing removes the old directory, so doesn't debugfs_create_dir() fail, resulting in subsequent failure to add any subsequent debugfs entries? I don't think this patch should be backported to stable trees until this point is addressed. -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!