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 D5AF8ECAAD4 for ; Mon, 29 Aug 2022 11:23:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231771AbiH2LXD (ORCPT ); Mon, 29 Aug 2022 07:23:03 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58310 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231642AbiH2LVy (ORCPT ); Mon, 29 Aug 2022 07:21:54 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A9A701165; Mon, 29 Aug 2022 04:14:11 -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 9964461214; Mon, 29 Aug 2022 11:11:14 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2889DC433C1; Mon, 29 Aug 2022 11:11:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1661771474; bh=VN7QLUM9u6R6IOVbvpnY/9cLJJiXJQxgKLVbZmB60TI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=bVaZDNlvo/t1l0Than623tRj/s0R1k8c5/53Qgg6sPT7HNfEtU6ev7TYvpsloSG/A 4p5Td4iZ1GjbRriz93f30orH47JnFuwv7OZmFipC9CKKQozPVAFqMjkW9xklNkF8cK FGMRT11KSCOHsa9vBni5u00boDmVIeWDGTJwQ7ew= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Badari Pulavarty , SeongJae Park , Andrew Morton Subject: [PATCH 5.15 107/136] mm/damon/dbgfs: avoid duplicate context directory creation Date: Mon, 29 Aug 2022 12:59:34 +0200 Message-Id: <20220829105809.108745359@linuxfoundation.org> X-Mailer: git-send-email 2.37.2 In-Reply-To: <20220829105804.609007228@linuxfoundation.org> References: <20220829105804.609007228@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Badari Pulavarty commit d26f60703606ab425eee9882b32a1781a8bed74d upstream. When user tries to create a DAMON context via the DAMON debugfs interface with a name of an already existing context, the context directory creation fails but a new context is created and added in the internal data structure, due to absence of the directory creation success check. As a result, memory could leak and DAMON cannot be turned on. An example test case is as below: # cd /sys/kernel/debug/damon/ # echo "off" > monitor_on # echo paddr > target_ids # echo "abc" > mk_context # echo "abc" > mk_context # echo $$ > abc/target_ids # echo "on" > monitor_on <<< fails Return value of 'debugfs_create_dir()' is expected to be ignored in general, but this is an exceptional case as DAMON feature is depending on the debugfs functionality and it has the potential duplicate name issue. This commit therefore fixes the issue by checking the directory creation failure and immediately return the error in the case. Link: https://lkml.kernel.org/r/20220821180853.2400-1-sj@kernel.org Fixes: 75c1c2b53c78 ("mm/damon/dbgfs: support multiple contexts") Signed-off-by: Badari Pulavarty Signed-off-by: SeongJae Park Cc: [ 5.15.x] Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman --- mm/damon/dbgfs.c | 3 +++ 1 file changed, 3 insertions(+) --- a/mm/damon/dbgfs.c +++ b/mm/damon/dbgfs.c @@ -376,6 +376,9 @@ static int dbgfs_mk_context(char *name) return -ENOENT; new_dir = debugfs_create_dir(name, root); + /* Below check is required for a potential duplicated name case */ + if (IS_ERR(new_dir)) + return PTR_ERR(new_dir); dbgfs_dirs[dbgfs_nr_ctxs] = new_dir; new_ctx = dbgfs_new_ctx();