From patchwork Fri Jun 17 05:09:03 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ian Kent X-Patchwork-Id: 12885095 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 BC4FFC43334 for ; Fri, 17 Jun 2022 05:15:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1379829AbiFQFPG (ORCPT ); Fri, 17 Jun 2022 01:15:06 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46958 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1379711AbiFQFPF (ORCPT ); Fri, 17 Jun 2022 01:15:05 -0400 Received: from smtp03.aussiebb.com.au (2403-5800-3-25--1003.ip6.aussiebb.net [IPv6:2403:5800:3:25::1003]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9630063BE8; Thu, 16 Jun 2022 22:15:03 -0700 (PDT) Received: from localhost (localhost [127.0.0.1]) by smtp03.aussiebb.com.au (Postfix) with ESMTP id CC5211A0081; Fri, 17 Jun 2022 15:09:04 +1000 (AEST) X-Virus-Scanned: Debian amavisd-new at smtp03.aussiebb.com.au Received: from smtp03.aussiebb.com.au ([127.0.0.1]) by localhost (smtp03.aussiebb.com.au [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id bDvF_O3hSklq; Fri, 17 Jun 2022 15:09:04 +1000 (AEST) Received: by smtp03.aussiebb.com.au (Postfix, from userid 119) id C349D1A009C; Fri, 17 Jun 2022 15:09:04 +1000 (AEST) Received: from donald.themaw.net (180-150-90-198.b4965a.per.nbn.aussiebb.net [180.150.90.198]) by smtp03.aussiebb.com.au (Postfix) with ESMTP id 30AAF1A0081; Fri, 17 Jun 2022 15:09:04 +1000 (AEST) Subject: [PATCH 1/2] vfs: parse: deal with zero length string value From: Ian Kent To: Al Viro Cc: Siddhesh Poyarekar , David Howells , Miklos Szeredi , Carlos Maiolino , linux-fsdevel , Kernel Mailing List Date: Fri, 17 Jun 2022 13:09:03 +0800 Message-ID: <165544254397.247784.17488951418549565189.stgit@donald.themaw.net> In-Reply-To: <165544249242.247784.13096425754908440867.stgit@donald.themaw.net> References: <165544249242.247784.13096425754908440867.stgit@donald.themaw.net> User-Agent: StGit/1.1 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org Parsing an fs string that has zero length should result in the parameter being set to NULL so that downstream processing handles it correctly. For example, the proc mount table processing should print "(none)" in this case to preserve mount record field count, but if the value points to the NULL string this doesn't happen. Signed-off-by: Ian Kent Reviewed-by: Christian Brauner (Microsoft) --- fs/fs_context.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/fs/fs_context.c b/fs/fs_context.c index 24ce12f0db32..4c735d0ce3cb 100644 --- a/fs/fs_context.c +++ b/fs/fs_context.c @@ -175,9 +175,13 @@ int vfs_parse_fs_string(struct fs_context *fc, const char *key, }; if (value) { - param.string = kmemdup_nul(value, v_size, GFP_KERNEL); - if (!param.string) - return -ENOMEM; + if (!v_size) + param.string = NULL; + else { + param.string = kmemdup_nul(value, v_size, GFP_KERNEL); + if (!param.string) + return -ENOMEM; + } param.type = fs_value_is_string; }