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 C4AC4C6FA8B for ; Thu, 15 Sep 2022 08:36:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230161AbiIOIfs (ORCPT ); Thu, 15 Sep 2022 04:35:48 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52118 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230336AbiIOIf3 (ORCPT ); Thu, 15 Sep 2022 04:35:29 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8A5A62B24F; Thu, 15 Sep 2022 01:35:28 -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 ams.source.kernel.org (Postfix) with ESMTPS id 47558B81E64; Thu, 15 Sep 2022 08:35:27 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7890AC433C1; Thu, 15 Sep 2022 08:35:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1663230926; bh=Ot/IEjx60+Ugq7shRIji6JO7/KL6tCs4ZKC7guXQRt0=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=qgxd2rrPMa9Ixwb8B6TmfT6+a8bvfq7DXh2qh2q0nOdD5SiAZE7WxVmRz8lt/mhdE wnK8C2jYiwfyWYgT+VQdbXA/ag/lVLk3/hIrUzBS+nHEhERppM0/O4fbyCjEn6kwKd QBWNBrdYv1VCO3gISmHYLFwVlfwLxfZU/FoNW3Lk= Date: Thu, 15 Sep 2022 10:35:51 +0200 From: Greg Kroah-Hartman To: "Russell King (Oracle)" 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: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Sep 13, 2022 at 05:48:58PM +0100, Russell King (Oracle) wrote: > 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. I'll drop this for now and get back to the fixup next week. thanks, greg k-h