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 9B452ECAAD5 for ; Fri, 2 Sep 2022 18:12:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229486AbiIBSMb (ORCPT ); Fri, 2 Sep 2022 14:12:31 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42128 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229437AbiIBSMa (ORCPT ); Fri, 2 Sep 2022 14:12:30 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A059F14094; Fri, 2 Sep 2022 11:12:29 -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 58FA0B82D01; Fri, 2 Sep 2022 18:12:28 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 38367C433D6; Fri, 2 Sep 2022 18:12:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1662142346; bh=E30b+14ku7Sf32GYr68BrvzpZrKcbccz0XGByZ9Zg9A=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=fB2mw+I83hOQ4LUp3b4wj8MNJ6whFO3s7CneREbnLn1ZmeR+z+GVpBDJuWjCTOxkk APXjVzkJ83/bl6yILOcty4K4QwmVEbB/5xbBmCqs+vTDQ2jfFvhH/PWtgvV0oPrKBj cusAh3f96ul5s5W8Rw+jKM44lXJWZAx3+zduKDSsG/Ph/SlLLRs/ZVigQrwATxN2h4 iyeVwrMTw8rFbQqrmBUaY/W+PdxdstiL5tpllOowQ7Zq5TuuKl5CpAYmLfqibmP6Vf TRVLJy1TsG4DiNRPhploGx/ZR3XzgUGTMYp2VTD3WislJhV9KMgECl2EAx3LjKIveL MBjqaExFPs41w== From: SeongJae Park To: Andrew Morton Cc: Greg Kroah-Hartman , SeongJae Park , linux-kernel@vger.kernel.org, damon@lists.linux.dev, linux-mm@kvack.org, stable , stable@vger.kernel.org Subject: Re: [PATCH] mm/damon/dbgfs: fix memory leak when using debugfs_lookup() Date: Fri, 2 Sep 2022 18:12:22 +0000 Message-Id: <20220902181222.83287-1-sj@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20220902091703.dcee7737e7ce8857e3235fa7@linux-foundation.org> References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org Hi Andrew and Greg! On Fri, 2 Sep 2022 09:17:03 -0700 Andrew Morton wrote: > On Fri, 2 Sep 2022 14:56:31 +0200 Greg Kroah-Hartman wrote: > > > When calling debugfs_lookup() the result must have dput() called on it, > > otherwise the memory will leak over time. Fix this up by properly > > calling dput(). Thank you for finding this bug and posting this patch, Greg! > > > > ... > > > > Fixes: 75c1c2b53c78b, I assume. Correct, Andrew. Fixes: 75c1c2b53c78b ("mm/damon/dbgfs: support multiple contexts") Cc: # 5.15.x > > > --- a/mm/damon/dbgfs.c > > +++ b/mm/damon/dbgfs.c > > @@ -915,6 +915,7 @@ static int dbgfs_rm_context(char *name) > > new_ctxs[j++] = dbgfs_ctxs[i]; > > } > > > > + dput(dir); > > kfree(dbgfs_dirs); > > kfree(dbgfs_ctxs); > > > > dput() is also needed if either of the kmalloc_array() calls fail? > Maybe something like Good catch. > > --- a/mm/damon/dbgfs.c~a > +++ a/mm/damon/dbgfs.c > @@ -884,6 +884,7 @@ static int dbgfs_rm_context(char *name) > struct dentry *root, *dir, **new_dirs; > struct damon_ctx **new_ctxs; > int i, j; > + int ret = 0; > > if (damon_nr_running_ctxs()) > return -EBUSY; > @@ -899,14 +900,12 @@ static int dbgfs_rm_context(char *name) > new_dirs = kmalloc_array(dbgfs_nr_ctxs - 1, sizeof(*dbgfs_dirs), > GFP_KERNEL); > if (!new_dirs) > - return -ENOMEM; > + goto out_dput; Shouldn't we also do 'ret = -ENOMEM;' before 'godo out_dput'? > > new_ctxs = kmalloc_array(dbgfs_nr_ctxs - 1, sizeof(*dbgfs_ctxs), > GFP_KERNEL); > - if (!new_ctxs) { > - kfree(new_dirs); > - return -ENOMEM; > - } > + if (!new_ctxs) > + goto out_new_dirs; ditto. > > for (i = 0, j = 0; i < dbgfs_nr_ctxs; i++) { > if (dbgfs_dirs[i] == dir) { > @@ -925,7 +924,13 @@ static int dbgfs_rm_context(char *name) > dbgfs_ctxs = new_ctxs; > dbgfs_nr_ctxs--; > > - return 0; > + goto out_dput; > + > +out_new_dirs: > + kfree(new_dirs); > +out_dput: > + dput(dir); > + return ret; > } > > static ssize_t dbgfs_rm_context_write(struct file *file, > _ Thanks, SJ