From patchwork Mon Jul 25 01:17:28 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ian Kent X-Patchwork-Id: 12927674 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 44EA9C433EF for ; Mon, 25 Jul 2022 01:17:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230099AbiGYBRk (ORCPT ); Sun, 24 Jul 2022 21:17:40 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39868 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231702AbiGYBRc (ORCPT ); Sun, 24 Jul 2022 21:17:32 -0400 Received: from smtp01.aussiebb.com.au (smtp01.aussiebb.com.au [121.200.0.92]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A6DD8BCA7; Sun, 24 Jul 2022 18:17:31 -0700 (PDT) Received: from localhost (localhost.localdomain [127.0.0.1]) by smtp01.aussiebb.com.au (Postfix) with ESMTP id 04B301003B6; Mon, 25 Jul 2022 11:17:30 +1000 (AEST) X-Virus-Scanned: Debian amavisd-new at smtp01.aussiebb.com.au Received: from smtp01.aussiebb.com.au ([127.0.0.1]) by localhost (smtp01.aussiebb.com.au [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 9MD8SgafrXJp; Mon, 25 Jul 2022 11:17:29 +1000 (AEST) Received: by smtp01.aussiebb.com.au (Postfix, from userid 116) id ECEBA100398; Mon, 25 Jul 2022 11:17:29 +1000 (AEST) Received: from donald.themaw.net (180-150-90-198.b4965a.per.nbn.aussiebb.net [180.150.90.198]) by smtp01.aussiebb.com.au (Postfix) with ESMTP id 23E271002FB; Mon, 25 Jul 2022 11:17:29 +1000 (AEST) Subject: [PATCH v3 2/2] vfs: parse: deal with zero length string value From: Ian Kent To: Al Viro Cc: Andrew Morton , Siddhesh Poyarekar , David Howells , Miklos Szeredi , Carlos Maiolino , linux-fsdevel , Kernel Mailing List Date: Mon, 25 Jul 2022 09:17:28 +0800 Message-ID: <165871184877.22404.8259055836221438535.stgit@donald.themaw.net> In-Reply-To: <165871154975.22404.9637671230578653457.stgit@donald.themaw.net> References: <165871154975.22404.9637671230578653457.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. Changes: v2: fix possible oops if conversion functions such as fs_param_is_u32() are called. Signed-off-by: Ian Kent --- fs/fs_context.c | 17 ++++++++++++----- fs/fs_parser.c | 16 ++++++++++++++++ include/linux/fs_context.h | 3 ++- 3 files changed, 30 insertions(+), 6 deletions(-) diff --git a/fs/fs_context.c b/fs/fs_context.c index 24ce12f0db32..df04e5fc6d66 100644 --- a/fs/fs_context.c +++ b/fs/fs_context.c @@ -96,7 +96,9 @@ int vfs_parse_fs_param_source(struct fs_context *fc, struct fs_parameter *param) if (strcmp(param->key, "source") != 0) return -ENOPARAM; - if (param->type != fs_value_is_string) + /* source value may be NULL */ + if (param->type != fs_value_is_string && + param->type != fs_value_is_empty) return invalf(fc, "Non-string source"); if (fc->source) @@ -175,10 +177,15 @@ 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; - param.type = fs_value_is_string; + if (!v_size) { + param.string = NULL; + param.type = fs_value_is_empty; + } else { + param.string = kmemdup_nul(value, v_size, GFP_KERNEL); + if (!param.string) + return -ENOMEM; + param.type = fs_value_is_string; + } } ret = vfs_parse_fs_param(fc, ¶m); diff --git a/fs/fs_parser.c b/fs/fs_parser.c index ed40ce5742fd..2046f41ab00b 100644 --- a/fs/fs_parser.c +++ b/fs/fs_parser.c @@ -197,6 +197,8 @@ int fs_param_is_bool(struct p_log *log, const struct fs_parameter_spec *p, struct fs_parameter *param, struct fs_parse_result *result) { int b; + if (param->type == fs_value_is_empty) + return 0; if (param->type != fs_value_is_string) return fs_param_bad_value(log, param); if (!*param->string && (p->flags & fs_param_can_be_empty)) @@ -213,6 +215,8 @@ int fs_param_is_u32(struct p_log *log, const struct fs_parameter_spec *p, struct fs_parameter *param, struct fs_parse_result *result) { int base = (unsigned long)p->data; + if (param->type == fs_value_is_empty) + return 0; if (param->type != fs_value_is_string) return fs_param_bad_value(log, param); if (!*param->string && (p->flags & fs_param_can_be_empty)) @@ -226,6 +230,8 @@ EXPORT_SYMBOL(fs_param_is_u32); int fs_param_is_s32(struct p_log *log, const struct fs_parameter_spec *p, struct fs_parameter *param, struct fs_parse_result *result) { + if (param->type == fs_value_is_empty) + return 0; if (param->type != fs_value_is_string) return fs_param_bad_value(log, param); if (!*param->string && (p->flags & fs_param_can_be_empty)) @@ -239,6 +245,8 @@ EXPORT_SYMBOL(fs_param_is_s32); int fs_param_is_u64(struct p_log *log, const struct fs_parameter_spec *p, struct fs_parameter *param, struct fs_parse_result *result) { + if (param->type == fs_value_is_empty) + return 0; if (param->type != fs_value_is_string) return fs_param_bad_value(log, param); if (!*param->string && (p->flags & fs_param_can_be_empty)) @@ -253,6 +261,8 @@ int fs_param_is_enum(struct p_log *log, const struct fs_parameter_spec *p, struct fs_parameter *param, struct fs_parse_result *result) { const struct constant_table *c; + if (param->type == fs_value_is_empty) + return 0; if (param->type != fs_value_is_string) return fs_param_bad_value(log, param); if (!*param->string && (p->flags & fs_param_can_be_empty)) @@ -268,6 +278,8 @@ EXPORT_SYMBOL(fs_param_is_enum); int fs_param_is_string(struct p_log *log, const struct fs_parameter_spec *p, struct fs_parameter *param, struct fs_parse_result *result) { + if (param->type == fs_value_is_empty) + return 0; if (param->type != fs_value_is_string || (!*param->string && !(p->flags & fs_param_can_be_empty))) return fs_param_bad_value(log, param); @@ -278,6 +290,8 @@ EXPORT_SYMBOL(fs_param_is_string); int fs_param_is_blob(struct p_log *log, const struct fs_parameter_spec *p, struct fs_parameter *param, struct fs_parse_result *result) { + if (param->type == fs_value_is_empty) + return 0; if (param->type != fs_value_is_blob) return fs_param_bad_value(log, param); return 0; @@ -287,6 +301,8 @@ EXPORT_SYMBOL(fs_param_is_blob); int fs_param_is_fd(struct p_log *log, const struct fs_parameter_spec *p, struct fs_parameter *param, struct fs_parse_result *result) { + if (param->type == fs_value_is_empty) + return 0; switch (param->type) { case fs_value_is_string: if ((!*param->string && !(p->flags & fs_param_can_be_empty)) || diff --git a/include/linux/fs_context.h b/include/linux/fs_context.h index 13fa6f3df8e4..ff1375a16c8c 100644 --- a/include/linux/fs_context.h +++ b/include/linux/fs_context.h @@ -50,7 +50,8 @@ enum fs_context_phase { */ enum fs_value_type { fs_value_is_undefined, - fs_value_is_flag, /* Value not given a value */ + fs_value_is_flag, /* Does not take a value */ + fs_value_is_empty, /* Value is not given */ fs_value_is_string, /* Value is a string */ fs_value_is_blob, /* Value is a binary blob */ fs_value_is_filename, /* Value is a filename* + dirfd */